That was what I got too but the answer sheet said the answer is increase by 83 1/3 percent

So the teacher who set the qn has language problem. The question should ask what is the percentage increase in the number of girls in the club

HAHAHHAHA ok

From 6 to 11. Increase is 5. Percentage increase is 5/6 ×100% =83.3%

Oh I see ok thanks

This is actually a textbook question.

By the way , this question doesn't really the usage of algebra.


Since the number of girls who left and the number of boys who left is the same, the total is unchanged (sounds familiar? P6 concept?)

Since the percentage of students who are girls increased to 50% , and 50% = 50/100 = ½ ,

½ of the students now are girls.

Number of girls at first = 22 × 3/11 = 6

Number of girls now = 22 × ½ = 11

Percentage increase in number of girls

= (11 - 6)/6 × 100%
= 5/6 × 100%
= 83⅓%


Number of new girls who joined = 11 - 6 = 5

The question is not phrased wrongly actually.

'What is the change in the percentage of girls in the club?' just means :

"what is the percentage change of girls in the club?"

Perhaps it would have been better to put commas for clarity and to omit 'the', and add 'in terms of'

i.e

"What is the change, in terms of percentage, of girls in the club?"


Change can be negative or positive. If this change is positive, simply leave the answer positive eg. 83⅓%

If the change was negative , leave it as negative


Eg. If 1 girl had left instead, there would be 5 girls left.

Percentage change = (final value - initial value)/initial value × 100%

= (5 - 6)/6 × 100%

= -1/6 × 100%

= -16 1/6%


What Yong Kc wrote in his working was actually answering this :

'what is the change in the percentage points for the number of girls in the club'

Oh thank u so much :))