Amachine stamps 50 metal parts in 15 minutes 30 seconds. find the unit rate in parts per hour.

Using proportions, it is found that the unit rate is of 194 parts per hour.

The rule of three is:

930 seconds - 50 parts

3600 seconds - x parts

Applying cross multiplication:

The unit rate is of 194 parts per hour.

A similar problem is given at link

193.55 parts  per hour

Step-by-step explanation:

We are given that a machine stamps 50 metal parts  

Time taken by machine=15 minutes 30 seconds

We have to find the unit rate in parts per hour

We know that 1 hour=3600 seconds

1 minute=60 seconds

15 minutes=seconds

Time=900+30=930 seconds

Time in hours=

Rate=

Rate=

Rate=193.55 parts  per hour

Hence, the unit rate =193.55 parts per hour

so mark-up is 0.4 multiplied by 180 = 72