A number is increased by 70 % and then decreased by 70 %. Find the net increase or decrease per cent.
OPtion
1) 56%
2) 25%
3) 35%
4) 46%
5) 48%
6) 49%
7) 53%
8) 52%
9) No change
10) None of the above
Solution
A number is increased by 70 % and then decreased by 70 %. Find the net increase or decrease per cent.
Let the number be 100.
Increase in the number = 70 % = 40 % of 100
= (40/100 × 100)
= 70
Therefore, increased number = 100 + 70 = 170
This number is decreased by 70 %
Therefore, decrease in number = 70 % of 170
= (70/100 × 170)
= 11900/100
= 119
Therefore, new number = 170 - 119 = 51
Thus, net decreases = 100 - 51 = 49
Hence, net percentage decrease = (49/100 × 100)
= (4900/100)
= 49 %