Question

Three students have started a fence-painting business. Working together, Pragnesh and Qazi can paint the fence in 2 hours. Similarly, Pragnesh and Ronghui can paint the fence in 3 hours when they work together. Finally, when Qazi and Ronghui work together, they can paint the fence in 4 hours. How long would it take if all three students worked together to paint the fence

Answer 1

Answer: 55.4 mins

Step-by-step explanation:

pragnesh and qazi = 2hrs

pragnesh and roghui = 3hrs

qazi and roghui = 4hrs

this means for every 1 hour they wold paint.

pragnesh and qazi = $\frac{1}{2}$ half of the fence

pragnesh and roghui = $\frac{1}{3}$

qazi and roghui = $\frac{1}{4}$ quarter of the fence

time taken when they all work together

= $\frac{1}{2}$ + $\frac{1}{3}$ + $\frac{1}{4}$

= $\frac{13}{12}$

= $\frac{12}{13}$

= 0.9231 × 60(mins)

= 55.4 mins