Question

Question 1
Four people are working to construct a 100m high wall. Each person can individually
construct the wall in 12 hours. All four people start working to construct the wall, but the
first person leaves once the wall is 25m high, the second person leaves once the wall is 50m
high and the third person leaves once the wall in 75m high. How much time does it take to
complete the construction of the entire wall?
A. 8 hours
B. 6 hours 15 min
C. 5 hours 45 min
D. 6 hours 20 min
​

Answer 1

Answer:

the answer will be B 6 hrs 15min

Step-by-step explanation:

first find the time taken by one person to construct a wall of 25m

which comes out to be 3hrs.

now since after every 25m one man left

the first 25m got build in 3/4 hrs

the second 25m in 3/3 hrs

the third 25m in 3/2 hrs

and the last 25m in 3 hrs

now add all the above

3/4+ 1+ 3/2 + 3

their sum comes out to be 25/4 hrs

now convert this into minutes

so total time = 375 min which is 6hrs and 15min