vikrantgulia
Richard receives an increment in his salary. His salary presently forms 30% of the total income of his family. Before the increment his salary used to form 20% of the total income of his family. By how many percentage points did the salary of Richard as a percentage of his family's total income increase?
A) 14(2/7)
B) 16(2/3)
C) 10
D) 8
E) 13(3/7)
The salary of Richard as a percentage of his family's total income was 20%
The salary of Richard as a percentage of his family's total income now is 30%
The
percentage points that have increased is 10 (from 20% to 30%).
Answer (C)
Now the question stem can be changed a little to change the entire solution. Let's look at two variations:
Variation 1: By what percent did the salary of Richard as a percentage of his family's total income increase?
Salary of Richard as a percentage of his family's total income was = 20%
Salary of Richard as a percentage of his family's total income now = 30%
The increase is from 20 to 30. This is an increase of 50% ( = (30 - 20)/20 * 100)
Variation 2: By what percent did the salary of Richard increase?
Say Richard's salary was = 20 and his family's total income was = 100
His salary increased by x and his family's total income also increased by x
(20+x)/(100+x) = 30/100
x = 100/7 = 14(2/7)
New salary of Richard = 20 + 14(2/7)
% increase in his salary = 14(2/7)/20 * 100 = 71.4%