Question

A concrete pump of 120-cy/hr max. output is used to place 250 cy of concrete. It is supplied by 8 cy transit-mix trucks arriving to the site every 15 mins. Barring interruptions how many hours will the operation require, considering 80% efficiency factor.

Answer 1

Answer:

Completing the operation will require 9.765625 hours.

Explanation:

First, let's check which of the stages will be the process limitation:

Regarding the pump, it can perform up to 120 cy/h. The trucks will deliver 8 cy every 15 min, i.e., 32 cy/h, then this is the smaller capacity within the whole process.

Now, let's establish a simple relation:

Placement speed x Efficiency = Placed quantity / time,

solving for time. we have

$t = \frac{q}{\epsilon s} = \frac{250 cy}{0.8\times 32\frac{cy}{h}} = \mathbf{9.765625 h}.$