when 6 boys were admitted and and 6 girls left the percentage of boys increased from 60 % to 75% .find tue original no.og boys and girls in the class. i know the answer but in which book can i find these type of questions?
Answers
Answer:
When 6 boys are admitted and 6 girls left, the percentage of boys increased from 60% to 75%. In this situation the original number of the boys is 24 and that of the girls is 16. The total number of the students is 40.
These type of questions are in the topic; 'Percentages, ratio and proportions.'
Step-by-step explanation:
Let the total number of students in this class be y
The original % of boys in that class = 60%
That means the boys were 60% of y = 60/100 × y = 0.6y
The original percentage of the girls = 40%
That means the girls were 40% of y = 40/100 of y = 0.4y
When six boys are admitted, 6 girls leave. That means the total number of students is the same ⇒ y + 6 - 6 = y
The new % of the boys in class is 75%.
This means boys are 75%of y = 75/100 × y = 0.75y
The original number of boys was 0.6 y, 6 were admitted and now we have 0.75y
Make an equation from this and find y
0.6y + 6 = 0.75y
0.6y - 0.75y = -6
-0.15y = - 6
y = -6/-0.15 = 40
y = 40
Therefore the total number of students in that class is 40.
Original number of boys = 60% of 40
= 60/100 × 40
= 24 boys
Original Number of girls = 40% of 40
= 40/100 × 40
= 16 girls