Question

Question #6c523

Answer 1

The speed of each chef is:

(`r`=recipe)

`v_A=(1r)/(5h)=0.2r/h`,

`v_B=(1r)/(2h)=0.5r/h`,

`v_C=(1r)/(2.5h)=0.4r/h`.

After `x` hours every chef will do `v*x` fraction of the recipe.

The three chef together in `x` hours will do:

`0.2r/h*x+0.5r/h*x+0.4r/h*x`.

But we want that the three chefs will do only `1r`, so:

`0.2r/h*x+0.5r/h*x+0.4r/h*x=1rrArr`

`1.1r/h*x=1rrArrx=1r*1/1.1h/r~=0.91h~=0.91*60min~=55min`.