Confusing Word Problems for Math Class :)

Question

- One team of worker can complete a job in 9 days, and the second team can complete the same job in 7 days. The first team worked for three days, and then the second team joined in. In how many days was the job completed?

 

- 2/3 of the water in a pool can be pumped out within 7.5 minutes by a particular pump. The pump worked for 0.15 hours and stopped. When it stopped, 25 m3 of water still remained in the pool. How much of the water was in the pool before the pump started working?

Answer 1

the first team completed 1/3 of the job working alone for 3 days. That leaves 2/3 of the job remaining.

 

Let x = days needed to complete the job

 

(1/9) x + (1/7)x = 2/3

 

7x + 9x = (2/3)(63)

 

16x = 42

 

x = 2.625 days

 

total days  = 5.625