# Time speed, work, Alligations and mixtures problems

Questions on time speed distance. 1. Trains are moving from A to B and B to A at regular interval of 1hr. They complete their journey in 5 hr. How many trains comming from station B will cross the train comming from station A that started at…

Questions on time speed distance.

1. Trains are moving from A to B and B to A at regular interval of 1hr. They complete their journey in 5 hr. How many trains comming from station B will cross the train comming from station A that started at 10am??Assume the trains starts from both the stations at the same time.

Alligations and Mixtures
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1. How do we identify what are weights and what are quantities in certian problems where time and speed are considered??

2. A mixture of certain quantity of Milk with 16L of water worth 90 paise per litre. If pure milk costs 108 paise per litre, what is the amount of milk in the mixture?

Regards,

Trains are moving from A to B and B to A at regular interval of 1hr. They complete their journey in 5 hr. How many trains comming from station B will cross the train comming from station A that started at 10am??Assume the trains starts from both the stations at the same time.
guess this was an easy one....just check out how much does it take for trn frm A to complete its journey...the question has it(5 hrs)...now during this journey all the trns that leave station B would meet this train at some place in the route....so one answer is 5 for trns laveing B at 10a, 11a, 12p, 1p, 2p...at 3p this trn reaches B....and one more trn leaves B at exactly the same time(eh...world of mathematics is so much ideal.....guess Indian railways learn frm this)...if we count this trn as well...we have 6 trns frm B which cross A...but i guess the answer shud be 5...whotsay.

How do we identify what are weights and what are quantities in certian problems where time and speed are considered??
really cudn't figure out what was this supposed to mean...can u please elaborate.

A mixture of certain quantity of Milk with 16L of water worth 90 paise per litre. If pure milk costs 108 paise per litre, what is the amount of milk in the mixture?
this one is agn easy...strt frm alligation...just have to assume water is free
let milk is x lts.

108(pure milk) 0(pure water)
\ /
90 (mixture of milk and water)
/ \
/ \
90(ratio for pure milk) 18(ratio for pure water)
x(actual quantity) 16(actual quantity of water)

So, x=80.

Questions on time speed distance
1.when a train move from st A at 10am so it will reach at B by 3pm while at the same time train moves from B at 10am, 11am, 12am, 1pm, 2pm so the ans is five....i think it was a bit simple if i m right

Alligations and Mixtures
1. sorry i didn't got ur question
2. quantity of cheap/quantity of dear=price of dear- mean prce/mean price-price of cheap

so here quantity of cheap=16L, price of cheap=0, price of dear=108paise, mean price of mixture =90paise...........16/x=18/90......80L of milk is there in mixture

The Answer for trains Question is 11.

Alligations ans is right!!

guess this was an easy one....just check out how much does it take for trn frm A to complete its journey...the question has it(5 hrs)...now during this journey all the trns that leave station B would meet this train at some place in the route....so one answer is 5 for trns laveing B at 10a, 11a, 12p, 1p, 2p...at 3p this trn reaches B....and one more trn leaves B at exactly the same time(eh...world of mathematics is so much ideal.....guess Indian railways learn frm this)...if we count this trn as well...we have 6 trns frm B which cross A...but i guess the answer shud be 5...whotsay.

really cudn't figure out what was this supposed to mean...can u please elaborate.

this one is agn easy...strt frm alligation...just have to assume water is free
let milk is x lts.

108(pure milk) 0(pure water)
\ /
90 (mixture of milk and water)
/ \
/ \
90(ratio for pure milk) 18(ratio for pure water)
x(actual quantity) 16(actual quantity of water)

So, x=80.

What is cheap and dear here?? Can tou please elaborate on this??

2. quantity of cheap/quantity of dear=price of dear- mean prce/mean price-price of cheap

so here quantity of cheap=16L, price of cheap=0, price of dear=108paise, mean price of mixture =90paise...........16/x=18/90......80L of milk is there in mixture

What is cheap and dear here?? Can tou please elaborate on this??

2. quantity of cheap/quantity of dear=price of dear- mean prce/mean price-price of cheap

so here quantity of cheap=16L, price of cheap=0, price of dear=108paise, mean price of mixture =90paise...........16/x=18/90......80L of milk is there in mixture

component of mixture one whose price is lower than other is cheap or below than the mean price of mixture & other one is dear means whose price is higher than the other component or mean price of mixture.....trains ans is 11:wow: plz elaborate

trains ans is 11 now i got it ...trains which are going to leave B at 5am, 6am, 7am, 8am, 9am, 10am, 11am, 12am, 1pm, 2pm, 3pm Questions on Time and Work

1. 20 women can finish a job in 20 days. After each day, one woman is replaced by a man or a boy alternatively starting with a man.Man is twice efficient and boy is half efficient as a woman,On which day does the job get completed??

2. A can do a job in 10 days. B can do the same job in 15 days. C can demolish the same job in 20 days. In how many days does the work get completed, if C starts the work and they work on alternate days as C-A-B-C and so on.

Questions on Time and Work

2. A can do a job in 10 days. B can do the same job in 15 days. C can demolish the same job in 20 days. In how many days does the work get completed, if C starts the work and they work on alternate days as C-A-B-C and so on.

C+A+B means three day work=1/20+1/10+1/15.......=13/60 this three days work done by c-a-b.......if 3 days work=13/60.....than 12 days work=52/60.....on 13th day 55/60 & on 14day the work will finish by A b'coz 55/60+1/10=61/60

2. the answer to second qustn shud be 26 5/7 days. since C is demolishing, she is as good as idle the first day. for a, b and c , in 3 days they finish

1/10 +1/15 - 1/20

so in 3 days they finish 7/60 of the work. so in all they would take 25 5/7 days + 1 day for the first once C spends.

1. for first question i think i need a pen and paper which i dont have right now at desk:huh:

without multiplying actually, is there a way to tell which is greater ..
say 61*94 and 92 * 65.
This comes in handy in DI.
Also , please tell me exactly how remebering reciprocals upto 30 will fhelp.
becasue i can calculate percentages by adjusting numerator and denominator until the denom is 100.

Is the answer of 2nd question "25 days".??
PLs let me know the correct answer so tht i can help.

Questions on Time and Work

1. 20 women can finish a job in 20 days. After each day, one woman is replaced by a man or a boy alternatively starting with a man.Man is twice efficient and boy is half efficient as a woman,On which day does the job get completed??

2. A can do a job in 10 days. B can do the same job in 15 days. C can demolish the same job in 20 days. In how many days does the work get completed, if C starts the work and they work on alternate days as C-A-B-C and so on.
Questions on Time and Work

1. 20 women can finish a job in 20 days. After each day, one woman is replaced by a man or a boy alternatively starting with a man.Man is twice efficient and boy is half efficient as a woman,On which day does the job get completed??

2. A can do a job in 10 days. B can do the same job in 15 days. C can demolish the same job in 20 days. In how many days does the work get completed, if C starts the work and they work on alternate days as C-A-B-C and so on.

Q1. 400 women hours r required.
there r 20 women hours every day.
If we replace by a man, then count goes up by 1 and if v replace by a boy count comes down by 0.5, so the series is--
20+21+20.5+21.5+21+22+21.5+22.5+22+23+22.5+23.5+23+24+23.5+24.5+24+18(25)=400

so no. of days = 17+(18/25) = 17.72 days answer.

Q2. Can u clear on C's part. i mean if he has to demolish what will he do on the first day????

1. 20 women can finish a job in 20 days. After each day, one woman is replaced by a man or a boy alternatively starting with a man.Man is twice efficient and boy is half efficient as a woman,On which day does the job get completed??

2. A can do a job in 10 days. B can do the same job in 15 days. C can demolish the same job in 20 days. In how many days does the work get completed, if C starts the work and they work on alternate days as C-A-B-C and so on.

1.assume total work = 800 units.
so a woman does 2 units of work in a day
man ..4 units...boy ..1 unit...

starting with 20 women intially..
day 1...40 units completed
day 2...38 + 4 = 42 units
day 3 ..36 + 1 + 4 = 41 units
day 4 ..34 + 1 + 8 = 43 units ..etc etc
day 5 ..32 + 2 + 8 = 42
day 6 ..30 + 2 +12 =44
now we hv to find in how many days this will add to 800 ...
easy way to do tht...
day 1 + day 2 = 82
day 3 + day 4 = 84
day 5 + day 6 = 86 ..etc... AP

in 18 days ... total work done = 9 (164 + 8*2)/2 = 9 (90) = 810
so work gets over on the 18th day...(u can calculate xact duration also)

2. assume 300 units of work..
so A = 30 units/day
B = 20 units/day
C = -15 units/day ...
so in a cycle of 3 days..cab total work done = 35 ...
in 8 cycles(24 days) .. 280 units .... 25 th day .. -15 ..so 265 ..then +30 ...295
on the 27 th day 5 units remaining..and B finfishes 20 units per day..
so in 1/4 of the day he will finish the work...
so ans 26.25 days.

edited: saw rajsher's post only after posting...good point..wht did C do on day 1....
did he mess things up so tht A had to do some cleaning up b4 starting work?? ..int ht case my soln is right..else.. we hv to take day 1 as 0...and count taking
nxt 3 days.....so ans wud be..25 2/3 as given... :confused:
andy .

Questions on Time and Work

2. A can do a job in 10 days. B can do the same job in 15 days. C can demolish the same job in 20 days. In how many days does the work get completed, if C starts the work and they work on alternate days as C-A-B-C and so on.

If we take this question as it is then answer is---

Day 1 - 0
next three days 1/10 + 1/15 - 1/20 = 7/60

so till 25 days work done is 56/60 and work left is 1/15

so the next day A will finish in (1/15)/(1/10) = 2/3 days

So answer 25 2/3 days

The correct answer is 25 2/3 days.

Is the answer of 2nd question "25 days".??
PLs let me know the correct answer so tht i can help.
The correct answer is 25 2/3 days.

thoda vistaar poorvak batao devi
mr_quipster Says
thoda vistaar poorvak batao devi

C the post number 15 above.
If u dont understand then main thoda aur vistaar se bataa doonga cheers,
Rajsher

In 3 days..work done = 7/60.

The Catch: C Starts with Zero work.. so he has nothing to demolish.
so in day 1 C does Zero Work. so the Patter is ABC..ABC....

In 24 days.. work done = 56/60...
so work left is 1/15. and days passed is 25.

Time taken by a to complete 1/15 th of work is 10/15 = 2/3

ie 252/3 days... pls correct me :)

1/15...

If we take this question as it is then answer is---

Day 1 - 0
next three days 1/10 + 1/15 - 1/20 = 7/60

so till 25 days work done is 56/60 and work left is 1/15
so next day, work left will be 1/15-1/20 = 1/60

next day a will finish in 1/6 days

So answer is 26 1/6 days