The price of electricity in the area where the Smith family lives is scheduled to increase by 20% next year. Since the Smith family cannot afford an increase in their electric bill, how much will they have to reduce consumption to keep their cost the same?
Choose the correct choice from the following options:
A) 30%
B) 25%
C) 16.7%
D) 20%
E) None
Solution: Let the current year's electrical expense be represented by Rs. 100.   The price of electricity rises 20%. So, to buy same amount of electricity, they need to increase their expense,   = (100 + 20% of 100) = Rs. 120.   But, they want to keep electricity expense the same, so they have to cut Rs. by 20 to keep it to Rs. =100.   The % decrease in consumption is,   (20/120)*100 = 20%.   Mental Calculation Method;   100-----20%↑---→120------X%↓---→100.   Here, X = (20/120)*100 = 16.7%.   Answer: Option 16.7%
<result>C</result>
The price of electricity in the area where the Smith family lives is scheduled to increase by 20% next year. Since the Smith family cannot afford an increase in their electric bill, how much will they have to reduce consumption to keep their cost the same?