Ratio, Proportion
- 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 ?
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Let original number of boys = 4N and number of girls = 5N
According to the question
(4N + 10)/5N = 6/5Correct Option: C
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
- The total number of student in a school is 8670. If the number of boys in the school is 4545, then what will be the ratio of the total number of boys to the total number of girls in the school ?
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Total number of student = 8670
Total number of boys = 4545
∴ Total number of girls = 8670 - 4545 = 4125Correct Option: A
Total number of student = 8670
Total number of boys = 4545
∴ Total number of girls = 8670 - 4545 = 4125
∴ Required ratio = 4545 : 4125 = 303 : 275
- A truck covers a distance 640 km in 10 h. A car covers the same distance in 8 h. What is the respective ratio of speed of the truck to that of car ?
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Speed of truck 640/10 = 64 km/h
Speed of car = 640/8 = 80 km/hCorrect Option: C
Speed of truck 640/10 = 64 km/h
Speed of car = 640/8 = 80 km/h
So, the required ratio = 64/80 = 4/5 = 4 : 5
- A person distributes his pens among four friends A, B, C, D in the ratio
that the person should have?= 1 : 1 : 1 : 1 What is the minimum number of pens 3 4 5 6
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A : B : C
= 1 : 1 : 1 : 1 3 4 5 6 = 1 × 60 : 1 × 60 : 1 × 60 : 1 × 60 3 4 5 6
[LCM of 3, 4, 5 & 6 = 60]
= 20 : 15 : 12 : 10
∴ Minimum number of pens
= 20 + 15 + 12 + 10 = 57Correct Option: A
A : B : C
= 1 : 1 : 1 : 1 3 4 5 6 = 1 × 60 : 1 × 60 : 1 × 60 : 1 × 60 3 4 5 6
[LCM of 3, 4, 5 & 6 = 60]
= 20 : 15 : 12 : 10
∴ Minimum number of pens
= 20 + 15 + 12 + 10 = 57
- If x : y = 3 : 4 and y : z = 3 : 4,
then x + y + z is equal to 3z
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x : y = 3 : 4 = 9 : 12
y : z = 3 : 4 = 12 : 16
∴ x : y : z = 9 : 12 : 16∴ x + y + z = 9k + 12k + 16k 3z 3 × 16k = 37 48 Correct Option: D
x : y = 3 : 4 = 9 : 12
y : z = 3 : 4 = 12 : 16
∴ x : y : z = 9 : 12 : 16∴ x + y + z = 9k + 12k + 16k 3z 3 × 16k = 37 48
