Q1. A group of workers can complete a certain job in 9 days. But it so happens that every alternate day starting from the second day, 2 workers are withdrawn from the job and every alternate day starting from the third day, one worker is added to the group. If it takes 17 days to finish the job now, find the number of workers who started the job? Q2. Two pipes A and B can fill a tank in 6hr and 9 hr respectively when working alone. A third pipe C can empty the same tank in 8hr. The pipes are operated such that A and C are open for the first couple of hours, then again B and C for the next 2 hr, again A and C for the next 2 hr, and so on. Operating in such a manner , if 68 L of water is filled in 30 hr, then find the volume of the tank. Q3. A can paint a wall in 11 days. How long would it take for B and C to paint the same wall together if it is known that to paint a smaller wall, individually, A took 6 days, B took 10 days and C took 12 days? Q4. It takes kim 4 hours to drive from her house to her office at her normal speed. If she reduces her speed by 3 kmph, she takes 40 min extra. Find the distance between Kim’s house and her office. Q5. In a kilometer race, A beats B by 200m and B beats C by 200m. Find the ratio between A’s and C’s speeds. Q6. A boat covers 6km upstream in 3 hours and a 20 km down stream in 2 hours. Find its speed in (km/hr) in still water? |
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1. b
2. a
3. a
4. b
6. a
Q5. In a kilometer race, A beats B by 200m and B beats C by 200m. Find the ratio between A’s and C’s speeds.
a. 5 : 4
b. 25 : 16
c. 4 : 3
d. 16 : 9
if A run 1000 then B run 800
but in 800 m race C just run 600m
so C run 750 in 1000m race so
speed ratio for A/C=1000/750=4/3
Little Star
n/a
Please put the solutions instead of just the answers
Thanks
Let u = speed of boat in still water
v = speed of water
then u + v = 20/2 = 10 km/hr
u - v = 6/3 = 2 km/hr
So u = 6 is the answer
Q4. It takes kim 4 hours to drive from her house to her office at her normal speed.
If she reduces her speed by 3 kmph, she takes 40 min extra.
Find the distance between Kim’s house and her office.?
ANS:
4u = (4 + 40/60)(u - 3)
=> 4u = 14/3 u - 14
=> (14/3 - 4)u = 14
=>2/3 u = 14
=> u = 21 kmph
So ditance = 21 x 4 = 84 km (ans b)
A can paint a wall in 11 days. How long would it take for B and C to paint the same wall together if it is known that to paint a smaller wall, individually, A took 6 days, B took 10 days and C took 12 days?
ANS:
A's efficiency = 16.66 %
B's efficiency = 10 %
C's efficiency = 8.33 %
No of days (B + C ) 'll take to complete the job that A completed in 11 days
= 11 x 16. 66/(18.33) = 10 days (ans a)
My answers are
Q1.
Q2. a
Q3. a
Q4. b
Q5. c
Q6. a
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