A can built up a structure in 8 days and B can break it in 3 days. A has worked for 4 days and then B joined to work with A for another 2 days only. In how many days will A alone built up the remaining part of the structure?
Possible Answers
12 days
9 days
10 days
None of these
pls show d entire process
A boat covers a distance of 30 kms. downstream in 2 hours while it takes 6 hours to cover the same distance upstream. What is the speed of the boat in kms per hour?
Possible Answers
18
7.5
13
5
pls show d entire process
1)A car travels 1/3 of the distance on a straight road with a velocity of 10 km/hr, next l/3rd with velocity 20 km/hr and the last l/3rd with velocity 60 km/hr. What is the average velocity of the car for the whole journey?
2)A plane left half an hour later than the sheduled time in order to reach its destination 1500 kms away in time,it had to increase its speed by 33.33 percent over the usual speed. Find increased speed
pls explain with steps thanks in advance
1.)answer of this is 18km/hr....
let distance be X
he covered X/3-------10km/hr-----1
X/3-----20km/hr------2
X/3------60km/hr----3
now apply formula for average speed
total distance/total time...
X/(X/30+X//60+X/180) and you will get your answer...
2.)my answer for 2nd one is 1000km/hr
let speed be X and time be T...
1500/X=T
and 1500/4X/3=T-1/2...
as with increased speed it will be able to cover this same distance in 30minutes less...solve this you will get your answer....
correct me if i am wrong somewhere...
1)A car travels 1/3 of the distance on a straight road with a velocity of 10 km/hr, next l/3rd with velocity 20 km/hr and the last l/3rd with velocity 60 km/hr. What is the average velocity of the car for the whole journey?
2)A plane left half an hour later than the sheduled time in order to reach its destination 1500 kms away in time,it had to increase its speed by 33.33 percent over the usual speed. Find increased speed
pls explain with steps thanks in advance
1. Let the distance be d.
Average velocity = Total Distance / Total time taken
=> Total time taken = (d/3) / 10 + (d/3)/20 + (d/3)/60
=> d/30 + d/60 + d/180
=> 6d + 3d + d / 180
=> 10d / 180
=> d / 18
=> Average velocity = d / (d/1
= 182. Distance remains constant here. Let speed be s and time taken be t
=> s * t = 133.33s/100 * (t-1/2)
=> st = 1.33s * (t-1/2)
=> 2st = 1.33s * 2t - 1.33s
=> 2t = 2.66t - 1.33
=> 0.66t = 1.33
=> t = 2
Hence original speed was 1500/2 = 750 km/hr
Now increased by 33.33%
=> 750 * 133.33/100 = 1000 km/hr (approx)
A boat covers a distance of 30 kms. downstream in 2 hours while it takes 6 hours to cover the same distance upstream. What is the speed of the boat in kms per hour?
Possible Answers
18
7.5
13
5
pls show d entire process
dude options are wrong...speed of stream will be 5km/hr and speed of boat will be 10km/hr....
let speed of boat is X
and speed of stream is Y
30/X+Y=2
30/X-Y=6 now solve this you will get your answer
A can built up a structure in 8 days and B can break it in 3 days. A has worked for 4 days and then B joined to work with A for another 2 days only. In how many days will A alone built up the remaining part of the structure?
your this question have been solved on earlier page...kindly look into it...and correct me if i am wrong somewhere...and ask if there is any problem...but do not post same repeated query again and again....
A boat covers a distance of 30 kms. downstream in 2 hours while it takes 6 hours to cover the same distance upstream. What is the speed of the boat in kms per hour?
Possible Answers
18
7.5
13
5
pls show d entire process
Let the speed of the boat be v and speed of stream be s.
For upstream relative speed will be (v-s) and for downstream relative speed will be (v+s)
=> 30 / (v+s) = 2
and 30 / (v-s) = 6
Solving we get,
v + s = 15 and v - s = 5
v = 10, s = 5
A can built up a structure in 8 days and B can break it in 3 days. A has worked for 4 days and then B joined to work with A for another 2 days only. In how many days will A alone built up the remaining part of the structure?
Possible Answers
12 days
9 days
10 days
None of these
pls show d entire process
A alone worked for 4 days.
Hence work done by A = (1/
* 4 = 1/2B joined for 2 days
Hence work done in these 2 days = (1/8 - 1/3) * 2 = -5/12
Total work done so far = 1/2 - 5/12 = 1/12
Now work remaining is 11/12
A can do 1 whole work in 8 days
A can do 11/12 work in 8 * 11/12 days = 7.3days
A boat covers a distance of 30 kms. downstream in 2 hours while it takes 6 hours to cover the same distance upstream. What is the speed of the boat in kms per hour?
Possible Answers
18
7.5
13
5
pls show d entire process
30/b+c=2
30/c-b=6
..if b=5 then c=10...
..so speed of boat is 5km/hr...:)
Let the speed of the boat be v and speed of stream be s.
For upstream relative speed will be (v-s) and for downstream relative speed will be (v+s)
=> 30 / (v+s) = 2
and 30 / (v-s) = 6
Solving we get,
v + s = 15 and v - s = 5
v = 10, s = 5
A alone worked for 4 days.
Hence work done by A = (1/* 4 = 1/2
B joined for 2 days
Hence work done in these 2 days = (1/8 - 1/3) * 2 = -5/12
Total work done so far = 1/2 - 5/12 = 1/12
Now work remaining is 11/12
A can do 1 whole work in 8 days
A can do 11/12 work in 8 * 11/12 days = 7.3days
dude i have adoubt in this step (1/8 - 1/3) * 2
we have used '-' in the place '+' coz B is breaking the work done by A and not building it ??am i right?? coz i solved it using '+' and got 11/6 as the answer..now after seeing ur steps..it rang a bell :-o..so just wanted to clarify it..
dude i have adoubt in this step (1/8 - 1/3) * 2
we have used '-' in the place '+' coz B is breaking the work done by A and not building it ??am i right?? coz i solved it using '+' and got 11/6 as the answer..now after seeing ur steps..it rang a bell :-o..so just wanted to clarify it..
Actually A is building it and B is breaking it simultaneously.
For A it will be (1/
and for B its (-1/3), so together it will become (1/8 + (-1/3))=> 1/8 - 1/3
So your logic is correct
Hope this clears you doubt Kittu ji!
Actually A is building it and B is breaking it simultaneously.
For A it will be (1/
=> 1/8 - 1/3
So your logic is correct
Hope this clears you doubt Kittu ji!
thanks alot ji 😃
speed of the upstream shud be v+s & speed of the downstream shud be v-s bcoz upstream is going against the stream and downstream is going according the stream..and we also know that the relative velocity of the 2 bodies moving in the same direction is represented by - and oppossite direction by +....pls clarify.
rahul005 Saysspeed of the upstream shud be v+s & speed of the downstream shud be v-s bcoz upstream is going against the stream and downstream is going according the stream..and we also know that the relative velocity of the 2 bodies moving in the same direction is represented by - and oppossite direction by +....pls clarify.
bhai simple sa concept or funda yaad rakhna in always upstream or downstream questions....in downstream we will reach early....so by formula D/S=T///
S should have be maximum...so it will be +
and just opposite in upstream..i hope now it is clear....
two cars started simultaneously towards each other from town A to B,that are 480 km apart.It took the first car traveling from A to B 8 hours to cover the distance and the second car traveling from B to A 12 hours.Determine the distance from A the two cars meet.
pls explain in detail with steps
two cars started simultaneously towards each other from town A to B,that are 480 km apart.It took the first car traveling from A to B 8 hours to cover the distance and the second car traveling from B to A 12 hours.Determine the distance from A the two cars meet.
pls explain in detail with steps
Clearly the speed of A will be 480/8 = 60 km/hr
and speed of B will be 480/12 = 40 km/hr
Now say they meet at a mutual point "X".
The car from A would have travelled x km to reach point "X" and the car at B would have travelled (480 - x) to reach the mutual point. Now in both the case the time at they meet will be the same.
Hence we equate time here,
=> x / 60 = (480 - x) / 40
=> 2x = 3*(480 - x)
=> 2x = 1440 - 3x
=> x = 288
Distance from A is 288 km.
two cars started simultaneously towards each other from town A to B,that are 480 km apart.It took the first car traveling from A to B 8 hours to cover the distance and the second car traveling from B to A 12 hours.Determine the distance from A the two cars meet.
pls explain in detail with steps
my take is 288 km....
A speed is 60km/hr
B speed is 40km/hr
now the time will meet at that time both would have traveld for same amount of time...
hence let the distance be X from A where they will meet and other will be 480-X...
X/60=480-X/40
solve this you will get your answer...
two trains for Patna leave Delhi at 6AM n 6:45AM and travel at 98 kph and 136 kph respectively. How many kilometers from delhi will two trains meet
in 45 minutes train a would have travelled a distance of 73km
therefore let time be t
then 73+98t=136t
t=73/38
now distance covered by train b 73/38*136=261.263
am i right..pls correct me if im wrong..they have not given the answer for this question
two trains for Patna leave Delhi at 6AM n 6:45AM and travel at 98 kph and 136 kph respectively. How many kilometers from delhi will two trains meet
in 45 minutes train a would have travelled a distance of 73km
therefore let time be t
then 73+98t=136t
t=73/38
now distance covered by train b 73/38*136=261.263
am i right..pls correct me if im wrong..they have not given the answer for this question
yes you are totally correct but woh 73 nahi...73.5 aayega...a small calculation mistake...
p.s.-aaj kal time speed and distance par work ho rha h...good due to you mera bhi revise ho rha hai...
so is the answr 7.5???
yes you are totally correct but woh 73 nahi...73.5 aayega...a small calculation mistake...
p.s.-aaj kal time speed and distance par work ho rha h...good due to you mera bhi revise ho rha hai...
yeah thank you ji...i thought i was wrong somewhere but was unable to find..thanks for ur complements..
Hi everyone,
I am having a few problems on numbers chapter in 'How to prepare for quantitative aptitude for the CAT" book by Arun Sharma.
I wanna discuss one by one.
Q) Find the greatest number of 4 digits which when divided by 10,11,15 and 22 leaves 3,4,8 and 15 as remainders respectively.
a) 9907 b) 9903
c) 9893 d) None of these.
Solution: First find the greatest 4 digit multiple of the LCM of 10,11,15 and 22. (In this case it is 9900). Then, Subtract 7 from it to give the answer.
This is the solution provided by the author itself. My Doubt in this is why should we subtract 7 number? why not any other number? What's the logic behind subtracting 7?
Thanks!
---------
The only thing that matters is the everlasting present.
:banghead::splat: