Number System problems
- 1. The product of two consecutive odd numbers is 19043. Which is the smaller one?
Options- A. 137
- B. 131
- C. 133
- D. 129 Discuss
Correct Answer: 137
Explanation:
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
- 2. If the three- fourth of number is subtracted from the number, the value so obtained is 163. What is that number?
Options- A. 625
- B. 562
- C. 632
- D. 652 Discuss
Correct Answer: 652
Explanation:
Let the number be N
According to the question
N - 3N/4 = 163
? N/4 = 163
? N = 652
- 3. A positive number, when increased by 10 equal 200 times its reciprocal . What is the number?
Options- A. 100
- B. 10
- C. 20
- D. 200 Discuss
Correct Answer: 10
Explanation:
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.
- 4. The sum of two numbers is 10. Their product is 20. Find the sum of the reciprocals of the two numbers.
Options- A. 1
- B. 3/5
- C. 1/2
- D. 11//6 Discuss
Correct Answer: 1/2
Explanation:
Here, M + N = 10 and MN = 20
According to the question,
(1/M) + (1/N) = (M + N) / MN = 10/20 = 1/2
- 5. Five time of a positive integer is equal to 3 less than twice the square of that number. Find the number?
Options- A. 3
- B. 13
- C. 23
- D. 33 Discuss
Correct Answer: 3
Explanation:
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.
- 6. A man has given one-fourth part of his property to his daughter, half part to his sons and one-fifth part given as charity. How much part of his property he has given?
Options- A. 1/20
- B. 19/20
- C. 1/10
- D. 9/10 Discuss
Correct Answer: 19/20
Explanation:
Total share given by a person
= (1/4) + (1/2) + (1/5)
= (5 + 10 + 4)/20
= 19/20
- 7. A chocolate has 12 equal piece. Monju gave 1/4 th of it to Anju, 1/3 rd of it to Sujata and 1/6 th of it to Fiza. The number of piece of chocolate left with Manju is?
Options- A. 1
- B. 2
- C. 3
- D. 4 Discuss
Correct Answer: 3
Explanation:
The number of pieces of chocolate left with Manju
= 1- [(1/4) + (1/3) + (1/6)
= 1 - (3 + 4 + 2)/12
= 1 - 9/12 = (12 - 9) / 12
= 3/12
- 8. A students was asked to multiply a number by 3/2 but he divided that number by 3/2. His result was therefore 10 less than the correct answer. Find the number?
Options- A. 10
- B. 12
- C. 15
- D. 20 Discuss
Correct Answer: 12
Explanation:
Let the number be N.
According to the question,
(N x 3)/2 - N / (3/2) = 10
? 3N/2 - 2N/3 = 10
? (9N - 4N) / 6 = 10
? 5N / 6 = 10
? N = (10 x 6)/5 = 12
- 9. What value should come in place of the question mark(?) in the following question?
√ ? /19 = 4?
Options- A. 76
- B. 5776
- C. 304
- D. 1296 Discuss
Correct Answer: 5776
Explanation:
Let √N/19 = 4
Then √N = 19 x 4 = 76
∴ N = 76 x 76 = 5776.
- 10. 4050/? ? = 450?
Options- A. 49
- B. 100
- C. 81
- D. 9 Discuss
Correct Answer: 81
Explanation:
Let 4050/?N = 450
Then ?N = 4050/450 = 9
? N = (9 x 9) = 81.
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