A number is first increased by 25% and then decreased by 10%. If the resulting number is 72, what is the original number?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 64
Resulting number = 72
Successive percentage change = x - y - xy/100 [Where x and y are percentage increase and decrease respectively]
Let the original number be a.
x = 25% increase
y = 10% decrease
Successive %change = 25 - 10 - ( 25 × 10/100 ) = 12.5% positive sign shows an increase.
ATQ -
x + 12.5% of x = 72
x + x/8 = 72
9x = 72(8)
x = 72(8)/9 = 64