Order of Magnitude problems
- 1. If x = ?3 + ?2, then the value of (x + 1)/(x - 1) - (x - 1)/(x + 1) is?
Options- A. ?3
- B. ?2
- C. ?6
- D. None of above Discuss
Correct Answer: ?2
Explanation:
(x + 1)/(x - 1) - (x - 1)/(x + 1) = {(x + 1)2 - (x - 1)2} / {(x - 1) (x + 1)}
= (x2 + 1 + 2x) - (x2 + 1 - 2x) / (x2 - 1)
= 4x / (x2 - 1) = 4(?3 + ?2) / {(?3 + ?2)2 - 1}
= 4(?3 + ?2) / (3 + 2 + 2?6 - 1) = 4(?3 + ?2) / (4 + 2 ?6)
= 4(?3 + ?2) / 2 ?2 (?3 + ?2)
= ?2
- 2. Which among ?8 and ?1000 is greater?
Options- A. ?8
- B. ?1000
- C. Both are equal
- D. None of these Discuss
Correct Answer: ?1000
Explanation:
?8 and ?1000 = 81/3 and 10001/3
Since 1000 > 8
? ?1000 > ?8
- 3. Which among ?81 and ?1 is smaller?
Options- A. ?81
- B. ?1
- C. Both are equal
- D. None of these Discuss
Correct Answer: ?1
Explanation:
?81 and ?1 = 811/2 and 11/2
Since, 1 < 81
? ?1 < ?81
- 4. IF (14) 3 is added to the square of a number, the answer to obtained is 4425. What is the number?
Options- A. 1849
- B. 43
- C. 41
- D. 1681 Discuss
Correct Answer: 41
Explanation:
Let the number be x.
According to the question,
x2 + (14)3 = 4425
? x2 = 4425 - (14)3
? x2 = 4425 - 2744
? x2 = 1681
? x = ?1681 = 41
- 5. Which among ?10 and ?8 is greater?
Options- A. ?10
- B. ?8
- C. Both are equal
- D. None of these Discuss
Correct Answer: ?8
Explanation:
?10 and ?8 = 101/4 and 81/3
Since, LCM of 4 and 3 is 12.
? 101/4 = 103/12 = (103)1/12 = (1000)1/12 = 12?1000
and 81/3 = 84/12 = (84)1/12 (4096)1/2 = 12?4096
? 4096 > 1000
Hence, 81/3 >101/4
? ?8 > ?10
- 6. Find the least number which multiplied with 74088 will make it a perfect square?
Options- A. 42
- B. 44
- C. 46
- D. 48 Discuss
Correct Answer: 42
Explanation:
74088 = 2 x 2 x 2 x 3 x 3 x 3 x 7 x 7 x 7
= (2 x 2) x (3 x 3) x (7 x 7) x ( 2 x 3 x 7)
? Least number which should be multiplied to 74088 to make it a perfect suqare = 2 x 3 x 7 = 42
- 7. Find the number whose square is equal to the difference between the square of 75.15 and 60.12.?
Options- A. 225.9
- B. 67.635
- C. 45.09
- D. 15.03 Discuss
Correct Answer: 45.09
Explanation:
Let the number be x.
Then, accordingto the question,
x2 = (75.15)2 - (60.12)2
? x2 = 5647.52 - 3614.41
? x2 = 2033.11
? x = 45.09
- 8. A general wishing to draw up his 16160 soldiers in the form as a solid square, found that he had 31 soldiers left over. Find the number of soldiers in the front.?
Options- A. 126
- B. 125
- C. 128
- D. 127 Discuss
Correct Answer: 127
Explanation:
Let the total number of soliders in front be x. Then, total number of soliders in form of solid square = x2
According to the question, x2 + 31 = 16160
? x2 = 16129 ? x = ?16129
? x = 127
- 9. A certain number of people agree to subscribe as many rupees each as there are subscribers. The whole subscription is Rs. 2582449. Find the number of subscriber.
Options- A. 1607
- B. 1291225
- C. 1503
- D. 1603 Discuss
Correct Answer: 1607
Explanation:
Let the total number of subbscribers be x.
Then, x2 = 2582449
? x = ?2582449 = 1607
- 10. Each student of class IX contributed some money for a picnic. The money contributed by each student was equal to the cube of the total number of student. If the total collected amount was Rs. 29791, then find the total number of students.
Options- A. 30
- B. 31
- C. 33
- D. 40 Discuss
Correct Answer: 31
Explanation:
Total collected amount = Rs. 29791
? Total number of student = ?29791 = 31
More in Aptitude:
Programming
Copyright ©CuriousTab. All rights reserved.