Number System
- The sum of two number is 29 and the difference of their squares is 145. The difference between the number is ?
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Let the number be a and b
Then, (a-b) = (a2 - b2) / a+bCorrect Option: B
Let the number be a and b
Then, (a-b) = (a2 - b2) / a+b
= 145/29
= 5
- The difference of two number is 5 and the difference of their squares is 135. The sum of the number is ?
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Let the number be a and b.
Then, (a + b) = (a2 -b2) / (a-b)Correct Option: A
Let the number be a and b.
Then, (a + b) = (a2 -b2) / (a-b)
= 135/5
= 27
- If 1 is added to the denominator of fraction, the fraction becomes 1/2. If 1 is added to the numerator, the fraction becomes 1. The fraction is ?
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Let the required fraction be x/y
Then, x/(y + 1) = 1/2
⇒ 2x - y = 1 ...(1)
(x + 1) / y = 1
⇒ x - y = -1 ...(2)Correct Option: C
Let the required fraction be x/y
Then, x/(y + 1) = 1/2
⇒ 2x - y = 1 ...(1)
(x + 1) / y = 1
⇒ x - y = -1 ...(2)
Solving Eq. (1) and (2)
We get x = 2, y = 3
∴ The fraction is 2/3
- 4/5 of a number exceeds its 2/3 by 8. The number is ?
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Let the number be x,
Then, 4x/5 - 2x/3 = 8Correct Option: B
Let the number be x,
Then, 4x/5 - 2x/3 = 8
⇒ (12x - 10x) / 15 = 8
⇒ 2x = 120
∴ x = 60
- If one-fourth of one-third of one-half of a number is 15, the number is ?
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Let the number be N .
Then, 1/4 of 1/3 of 1/2 of N = 15
⇒ 1/4 x 1/3 x 1/2 x N = 15Correct Option: D
Let the number be N .
Then, 1/4 of 1/3 of 1/2 of N = 15
⇒ 1/4 x 1/3 x 1/2 x N = 15
⇒ N/24 = 15
⇒ N = 24 x 15 = 360 .