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- Question
The sum of the digits of a two-digit number is 15 and the difference between the digits is 3. What is the two-digit number?
Options- A. 69
- B. 78
- C. 96
- D. Cannot be determined
- E. None of these
- Correct Answer
- Cannot be determined
ExplanationLet the ten's digit be x and unit's digit be y.Then, x + y = 15 and x - y = 3 or y - x = 3.
Solving x + y = 15 and x - y = 3, we get: x = 9, y = 6.
Solving x + y = 15 and y - x = 3, we get: x = 6, y = 9.
So, the number is either 96 or 69.
Hence, the number cannot be determined.
More questions
- 1. At simple interest, a sum becomes 3 times in 20 yr. Find the time, in which the sum will be double at the same rate of interest.
Options- A. 8 yr
- B. 10 yr
- C. 12 yr
- D. 14 yr Discuss
Correct Answer: 10 yr
Explanation:
Here, n = 3, m = 2, T1 = 20 yr
? T2 = [(m -1) / (n - 1)] x T1
= (2 - 1) / (3 - 1) x 20 = 10 yr- 2. 5, 10, 13, 26, 29, 58, 61, (....)
Options- A. 122
- B. 64
- C. 125
- D. 128 Discuss
Correct Answer: 122
Explanation:
Numbers are alternatively multiplied by 2 and increased by 3.So, the missing number = 61 x 2 = 122.
- 3. The sum of the present ages of a father and his son is 60 years. Six years ago, father's age was five times the age of the son. After 6 years, son's age will be:
Options- A. 12 years
- B. 14 years
- C. 18 years
- D. 20 years Discuss
Correct Answer: 20 years
Explanation:
Let the present ages of son and father be x and (60 -x) years respectively.Then, (60 - x) - 6 = 5(x - 6)
⟹ 54 - x = 5x - 30
⟹ 6x = 84
⟹ x = 14.
∴ Son's age after 6 years = (x+ 6) = 20 years..
- 4. A man wants to sell his scooter. There are two offers, one at Rs. 12,000 cash and the other a credit of Rs. 12,880 to be paid after 8 months, money being at 18% per annum. Which is the better offer?
Options- A. Rs. 12,000 in cash
- B. s. 12,880 at credit
- C. Both are equally good Discuss
Correct Answer: Rs. 12,000 in cash
Explanation:
P.W. of Rs. 12,880 due 8 months hence = Rs. [ 12880 x 100 ] 100 + ❨ 18 x 8 ❩ 12 = Rs. ❨ 12880 x 100 ❩ 112 = Rs. 11500. - 5. 5/12 part of what amount will be equal to 33/4 part of ? 100?
Options- A. ? 900
- B. ? 940
- C. ? 875
- D. ? 975 Discuss
Correct Answer: ? 900
Explanation:
Let the amount be ? a
According to the question,
a x 5/12= 33/4 x 100
? 5a/12 = 15/4 x 100
? a = 12/5 x 15/4 x 100
? a = 12 x 15 x 100/4 x 5
? a = ? 900- 6. Which of the following equations is a quadratic?
Options- A. x3 - x2 - x + 5 = 0
- B. x4 - 10
- C. 7x2 = 49
- D. x4 - x3 = 9000 Discuss
Correct Answer: 7x2 = 49
Explanation:
Clearly, 7x2 = 49 or 7x2 - 49 = 0, which is of the form ax2 + bx + c = 0, where b = 0.
Thus, 7x2 - 49 = 0 is a quadratic equation.- 7. A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left is :
Options- A.
1 4 - B.
1 10 - C.
7 15 - D.
8 15
Discuss
Correct Answer:8 15
Explanation:
A's 1 day's work = 1 ; 15 B's 1 day's work = 1 ; 20 (A + B)'s 1 day's work = ❨ 1 + 1 ❩ = 7 . 15 20 60 (A + B)'s 4 day's work = ❨ 7 x 4 ❩ = 7 . 60 15 Therefore, Remaining work = ❨ 1 - 7 ❩ = 8 . 15 15 - 8. If 7 spiders make 7 webs in 7 days, then 1 spider will make 1 web in how many days?
Options- A. 1
- B. 7⁄2
- C. 7
- D. 49 Discuss
Correct Answer: 7
Explanation:
Let the required number days be xLess spiders, More days (Indirect Proportion)
Less webs, Less days (Direct Proportion)
Spiders 1 : 7 ] :: 7 : x Webs 7 : 1 ∴ 1 x 7 x x = 7 x 1 x 7
⟹ x = 7.
- 9. A train passes two persons two persons who are walking in the direction opposite to the direction of train at the rate of 10 m/s and 20 m/s respectively in 12 s and 10 s, respectively. Find the length of the train?
Options- A. 500 m
- B. 900 m
- C. 400 m
- D. 600 m Discuss
Correct Answer: 600 m
Explanation:
Let the speed of the train be V
According to the question.
(V + 10) x 12 = (V + 20) x 10
? 6V + 60 = 5V + 100
? x = 100 - 60 = 40 m/s
? Length of the train = (V + 10) x 12
= (40 + 10) x 12 = 600 m- 10. A tank is filled in 5 hours by three pipes A, B and C. The pipe C is twice as fast as B and B is twice as fast as A. How much time will pipe A alone take to fill the tank?
Options- A. 20 hours
- B. 25 hours
- C. 35 hours
- D. Cannot be determined
- E. None of these Discuss
Correct Answer: 35 hours
Explanation:
Suppose pipe A alone takes x hours to fill the tank.Then, pipes B and C will take x and x hours respectively to fill the tank. 2 4 ∴ 1 + 2 + 4 = 1 x x x 5 ⟹ 7 = 1 x 5 ⟹ x = 35 hrs.
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