Advertisements
Advertisements
Question
In class X of a school, the ratio of the number of boys to that of the girls is 4 : 3. If there were 20 more boys and 12 less girls, then the ratio would have been 2 : 1, How many students were there in the class?
Advertisements
Solution
Let the number of students in the class = x
Ratio of boys and girls = 4 : 3
∴ No. of boys = `(4x)/(7)`
and no. of girls = `(3x)/(7)`
According to the problem,
`((4x)/7 + 20) : ((3x)/7 - 12)` = 2 : 1
`(4x + 140)/(7) : (3x - 84)/(7)` : 2 : 1
⇒ `(4x + 140)/(7) xx (7)/(3x - 84) = (2)/(1)`
⇒ `(4x + 140)/(3x - 84) = (2)/(1)`
⇒ 6x – 168 = 4x + 140
⇒ 6x – 4x = 140 + 148
⇒ 2x = 308
⇒ x = `(308)/(2)` = 154
Hence, number of students = 154.
APPEARS IN
RELATED QUESTIONS
If 60% people in city like cricket, 30% like football, and the remaining like other games, then what percentage of the people like other games? If the total number of people is 50 lakh, find the exact number who like each type of game.
If m : n = 3 : 8, find the value of (3m+2n) : (5m+n)
If x2, 4 and 9 are in continued proportion, find x.
Find the value of x, when 2.5 : 4 = x : 7.5.
The ratio of the number of girls to the number of boys in a school is 2 : 5. If the number of boys is 225; find:
(i) the number of girls in the school.
(ii) the number of students in the school.
A factory produces electric bulbs. If 1 out of every 10 bulbs is defective and the factory produces 630 bulbs per day, find the number of defective bulbs produced each day.
|
Distance from Mary’s home to school (in km.)
|
10 | 4 | |||
|
Distance from John’s home to school (in km.)
|
5 | 4 | 3 | 1 |
Ratio of 3 m to 200 cm = _____________
Given below is a Mathematical term.
Find the ratio of consonants to vowels in the term.
The ratio of 60 to 48, when reduced to its simplest form, is:
