Number System
- A mason can build a wall in 70 hours. After 7 hours he takes a break. What fraction of the wall is yet to be built?
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∵ A mason makes a wall in 70 hours.
∴ Part of wall built by the mason in 7 hours = 7 70 = 1 10 ∴ Remaining part = 1 – 1 10 = 9 = 0.9 10 Correct Option: A
∵ A mason makes a wall in 70 hours.
∴ Part of wall built by the mason in 7 hours = 7 70 = 1 10 ∴ Remaining part = 1 – 1 10 = 9 = 0.9 10
- If
4 th of a number exceeds its 5 3 th by 8, then the number is : 4
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Let the number be x.
According to the question,4x = 3x = 8 5 4 ⇒ 16x − 15x = 8 20 ⇒ x = 8 20
⇒ x = 20 × 8 = 160Correct Option: C
Let the number be x.
According to the question,4x = 3x = 8 5 4 ⇒ 16x − 15x = 8 20 ⇒ x = 8 20
⇒ x = 20 × 8 = 160
- If 1/2 is added to a number and the sum is multiplied by 3, the result is 21. Then the number is :
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x + 1 × 3 = 21 2 ⇒ x + 1 = 21 = 7 2 3 ⇒ x = 7 – 1 = 13 = 6.5 2 2 Correct Option: A
x + 1 × 3 = 21 2 ⇒ x + 1 = 21 = 7 2 3 ⇒ x = 7 – 1 = 13 = 6.5 2 2
- The sum of three numbers is 2, the 1st number is 1/2 times the 2nd number and the 3rd number is 1/4 times the 2nd number. The 2nd number is
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Let second number be x.
∴ First number = x 2 Third number = x 4 ∴ x + x + x = 2 2 4 ⇒ 4x + 2x + x = 2 4 ⇒ 7x = 8 ⇒ x = 8 7
Correct Option: B
Let second number be x.
∴ First number = x 2 Third number = x 4 ∴ x + x + x = 2 2 4 ⇒ 4x + 2x + x = 2 4 ⇒ 7x = 8 ⇒ x = 8 7
- The numerator of a fraction is multiple of two numbers. One of the numbers is greater than the other by 2. The greater number is smaller than the denominator by 4. If the denominator 7 + c (c > –7) is a constant, then the minimum value of the fraction is
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Let the first number be x.
∴ Second number = x + 2
According to the question,
x + 2 = 7 + c – 4 = 3 + c
⇒ x = 1 + c
∴ Fraction= x(x + 2) = (1 + c) (3 + c) 7 + c 7 + c
For the minimum value,
–3 < c < –1
∴ c = –2
∴ Required value of fraction = –∴ Required value of fraction = – 1 5 Correct Option: D
Let the first number be x.
∴ Second number = x + 2
According to the question,
x + 2 = 7 + c – 4 = 3 + c
⇒ x = 1 + c
∴ Fraction= x(x + 2) = (1 + c) (3 + c) 7 + c 7 + c
For the minimum value,
–3 < c < –1
∴ c = –2
∴ Required value of fraction = –∴ Required value of fraction = – 1 5