Time speed, work, Alligations and mixtures problems

[madhavi]

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
--------------------------

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,
Madhavi

[catholicon]

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.

[sumitkatlana]

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

[madhavi]

The Answer for trains Question is 11.

Alligations ans is right!!

Originally Posted by catholicon

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.

[madhavi]

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[/quote]

[sumitkatlana]

Originally Posted by madhavi

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 plz elaborate

[sumitkatlana]

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

[madhavi]

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.

[sumitkatlana]

Originally Posted by madhavi

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

[mr_quipster]

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