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?
Answers
C h a r g e s space f o r space p r i v a t e space u s e space p e r space h o u r equals space £ 5 space C h a r g e s space f o r space r e s e a r c h space w o r k space p e r space h o u r equals £ 15 C h a r g e s space f o r space c o m m e r c i a l space w o r k space p e r space h o u r equals £ 40 M a c h i n e space i s space o p e r a t e d space 8 space h o u r s space i n space a space 5 space d a y space w e e k. A l s o space g i v e n space t h a t space t h e space n u m b e r space o f space h o u r s space c h a r g e d space a t space t h e space f i r s t comma space s e c o n d space a n d space t h i r d space r a t e s space a r e space i n space r a t i o s space 4 colon 2 colon 1 T h u s comma C h a r g e s space f o r space p r i v a t e space u s e space i n space a space p a r t i c u l a r space w e e k equals 4 cross times 5 cross times 5 equals £ 100 C h a r g e s space f o r space space r e s e a r c h space w o r k space i n space a space p a r t i c u l a r space w e e k equals 2 cross times 15 cross times 5 equals £ 150 C h a r g e s space f o r space space c o m m e r c i a l space w o r k space i n space a space p a r t i c u l a r space w e e k equals 1 cross times 40 cross times 5 equals £ 200 T o t a l space c h a r g e s space i n space a space p a r t i c u l a r space w e e k equals £ open parentheses 100 plus 150 plus 200 close parentheses space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space equals £ 450 P e r c e n t a g e space o f space c h a r g e s space o f space c o m m e r c i a l space w o r k space i n space t o t a l space r e c e i p t s equals 200 over 450 cross times 100 equals 44.5 percent sign space