Question

A machine that cost £35,000 is operated 8 hours a day in a 5-day week but one hour each day is used for test purposes. For use of the machine there are three scales of charges, the first at the rate of £5 an hour for private use, the second at £15 an hour for research work and the third at £40 an hour for commercial work. It is estimated that the number of hours charged at the first, second and third rates are in ratios 4:2:1. What percentage of total receipts do receipts from commercial work represent?

Answer 1

1 hour each day is used for test
so 8-1=7 used per day

so commercial is 1 in the 4:2:1 so
4+2+1=7
ok, so 7 units, 7 hours
4 hour for private
2 hour for research
1 hour of commerical

4*5=20=private
2*15=30=research
1*4=40=commercial


20+30+40=90

percent from commercial
40/90=0.44444444444≈44.44% about 44%

Answer 2

Charges for private use in particular week=4*5*5=100
Charges for research work in particular week=2*15*5=150
Charges for commercial work in a particular week=1*40*5=200
Total charges in a particular week=100+150+200=450
Percentage of charges of commercial work in total receipts=(200/450)*100=44.4%