Question 1: The strength of a school increases and decreases in every alternate year by 10%. It started with increase in 2000. Then, the strength of the school in 2003 as compared to that in 2000 was
(a) increased by 8.9%
(b) decreased by 8.9%
(c) increased by 9.8%
(d) decreased by 9.8%
Answers and Explanations
Answer 1: a
Let the strength of school in 2000 is 100.
According to question, in year 2001 strength increased by 10%
So, new strength = {100 x (100 + 10)/100} = 110
In year 2002, strength decreased by 10%
So, new strength ={100 x (100 – 10)/100} = 99
Again in year 2003, it increased by 10%
So, new strength = {99 x (100 + 10)/100} = 108.9
Percentage Change = {(108.9 – 100)/100} x 100 = 8.9%
The strength in 2003 as compared to 2000 is increased by 8.9%.
Question 2: A number is increased by 10% and then the increased number is decreased by 10%. The net increase or decrease is
(a) increased by 2%
(b) decreased by 1%
(c) increased by 10%
(d) decreased by 10%
Answers and Explanations
Answers: (b)
Percentage change formula when a number is first increased by x% and then decreased by y%
{x – y – (xy/100)}%
Here, x = 10% and y = 10%
Percentage change= {10 – 10 – (10 x 10)/100} = -1%
Thus, there is 1% decrease.
Question 3: During the first year the population of a village is increased by 5% and the second year it is diminished by 5%. At the end of the second year its population was 47880. What was the population at the beginning of the first year?
(a) 45500
(b) 48000
(c) 43500
(d) 53000
Answers and Explanations
Question 4: When the price of article was reduced by 20% its sale increased by 80%. What was the net effect on the revenue?
(a) 44% increase
(b) 44% decrease
(c) 66% increase
(d) 75% increase
Answers and Explanations
Question 5: Two successive price increases of 10% and 10% of an article are equivalent to a single price increase of
(a) 19%
(b) 20%
(c) 21%
(d) 22%
Answers and Explanations
Percentages: The Complete Lesson
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