In a class the number of boys and girls is in the ratio of 4 : 5. If 10 more boys join the class, the ratio of numbers of boys and girls become 6 : 5. How many girls there in the class?
Correct Answer: 25
Explanation:
Let original number of boys = 4N and number of girls = 5N
According to the question
(4N + 10)/5N = 6/5
⇒ 30N = 20N + 50
⇒ 10N = 50
∴ N = 50/10 = 5
∴ Number of girls = 5N = 5 x 5 = 25
