Maths Class 5 Fractions

Asked by AKSHAY GURU VARADHARAJAN · SRI CHAITANYA TECHNO SCHOOL, JAYANTI NAGAR.

A combination lock requires 3 numbers to unlock. The second number is 2/5 of the first number. The third number is 3/4 of the second number. The difference between the first number and the third number is 42. What is the second number?

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A 60
B 24
C 14
D 34

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Answer: B. 24

Let the first number be x. The second number is 2/5 x. The third number is 3/4 x 2/5 x = 3/10 x.
x - 3/10 x = 42, so 7x/10 = 42 and x = 60.
Second number = 2/5 x 60 = 24.

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A combination lock requires 3 numbers to unlock. The second number is 2/5 of the first number. The third number is 3/4 of the second number. The difference between the first number and the third number is 42. What is the second number?

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