Question

(a) You have completed the mathematics project in 20 days. How many days will your friend take to

complete the same work if he is 20% less efficient than you? (2)

(b) Both of you can together finish the mathematics project in 16 days. After working together for 8

days, your friend left. The remaining part of the project was finished by you in 10 days. In how

many days you alone can finish the project?​

Answer 1

Answer:

a) 25 days

b) 20 days

Step-by-step explanation:

a) He is 20% less efficient so he is 80% efficient

So, if I do x work in 20 days, I do x/20 work in a day (unitary method)

Work he can do in 1 day = 80% of mine = 4/5 * x/20 = x/25

so he will complete the work in 25 days.

b) Let the total work be y now,

So we together complete y/16 work in a day

for 8 days, we did y/2 work.

Now remaining y/2 work I did in 10 days

So I could have done y work in 20 days all alone.