Number System
- The product of two consecutive odd numbers is 19043. Which is the smaller one?
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Let the two consecutive numbers are N and N+2
According to the question
N (N + 2) = 19043Correct Option: A
Let the two consecutive numbers are N and N+2
According to the question
N (N + 2) = 19043
⇒ N2 + 2N - 19043 = 0
⇒ N2 + 139N - 137N - 19043= 0
⇒ N( N + 139) - 137 ( N - 137 ) = 0
⇒ N( N + 139) ( N - 137) = 0
⇒ N = 137 and N = - 139
∴ N = 137
- If the three- fourth of number is subtracted from the number, the value so obtained is 163. What is that number?
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Let the number be N
According to the question
N - 3N/4 = 163Correct Option: D
Let the number be N
According to the question
N - 3N/4 = 163
⇒ N/4 = 163
∴ N = 652
- A positive number, when increased by 10 equal 200 times its reciprocal . What is the number?
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Let the positive number be N.
According to the question,
N + 10 = 200/N
⇒ N2 + 10N = 200Correct Option: B
Let the positive number be N.
According to the question,
N + 10 = 200/N
⇒ N2 + 10N = 200
⇒ N2 + 10N - 200 = 0
⇒ ( N - 10) ( N + 20) = 0
&ythere4; N = 10 and N = -20
But N ≠ -20, since N is a positive number.
So, the required number is 10.
- The sum of two numbers is 10. Their product is 20. Find the sum of the reciprocals of the two numbers.
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Here, M + N = 10 and MN = 20
According to the question,
(1/M) + (1/N) = (M + N) / MNCorrect Option: C
Here, M + N = 10 and MN = 20
According to the question,
(1/M) + (1/N) = (M + N) / MN = 10/20 = 1/2
- Five time of a positive integer is equal to 3 less than twice the square of that number. Find the number?
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Let the number be N.
According to the question,
⇒ 5N = 2N2 - 3Correct Option: A
Let the number be N.
According to the question,
⇒ 5N = 2N2 - 3
⇒ 2N2 - 5N - 3 = 0
⇒ (N - 3) ( 2N + 1 ) = 0
N = 3 and N = -1/2
Thus, the required number is 3.