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- Question
A is thrice as good as workman as B and therefore is able to finish a job in 60 days less than B. Working together, they can do it in:
Options- A. 20 days
- B.
22 1 days 2 - C. 25 days
- D. 30 days
- Correct Answer
-
22 1 days 2
ExplanationRatio of times taken by A and B = 1 : 3.The time difference is (3 - 1) 2 days while B take 3 days and A takes 1 day.
If difference of time is 2 days, B takes 3 days.
If difference of time is 60 days, B takes ❨ 3 x 60 ❩ = 90 days. 2 So, A takes 30 days to do the work.
A's 1 day's work = 1 30 B's 1 day's work = 1 90 (A + B)'s 1 day's work = ❨ 1 + 1 ❩ = 4 = 2 30 90 90 45 ∴ A and B together can do the work in 45 = 22 1 days. 2 2
More questions
- 1. How long will a sum of money invested at 5% per annum SI take to increase its value by 50%
Options- A. 10 yr
- B. 12 yr
- C. 15 yr
- D. 7 yr Discuss
Correct Answer: 10 yr
Explanation:
Let sum be P.
? 50% of P = P/2 = SI
Now, P/2 = (P x 5 x T) / 100 [ as time = 10 yr]
? P/2 = 5PT / 100
? 1/2 = T/20
? = T = 10 yr- 2. The radius of a circle is so increased that its circumference increased by 5%. The area of the circle, then increases by
Options- A. 12.5%
- B. 10.25%
- C. 10.5 %
- D. 11.25% Discuss
Correct Answer: 10.25%
Explanation:
Increase in circumference of circle = 5%
? Increase in radius is also 5%.
Now, increase in area of circle = 2a + (a2/100) %
Where, a = increase in radius= 2 x 5 + (5 x 5)/100 % = 10.25%- 3. In a class, there are 80 students and their average marks in the annual examination are 40. If the average marks of passed students are 60 and average marks of failed students are 35, then find out the number of students who failed.
Options- A. 63
- B. 60
- C. 72
- D. 64 Discuss
Correct Answer: 64
Explanation:
Let the number of failed student = Y
? Number of passed student = 80 - Y
sum of marks of all students = sum of marks of passed students + sum of marks of failed students
80 x 40 = (80 - Y) x 60 + 35Y
? 3200 =4800 - 60Y + 35Y
? 25Y = 1600
? Y = 64
? Number of students who failed = 64- 4. 2 men or 5 women or 7 boys can finish a work in 469 days, then the number of days taken by 7 men, 5 women and 2 boys to finish the work is :
Options- A. 134
- B. 106
- C. 100
- D. 98 Discuss
Correct Answer: 98
Explanation:
2 men = 7 boys
? 1 man = 7/2 days
5 women = 7 boys
? 1 women = 7/5 boys
7 men + 5 women + 2 boys = 7 x 7/2 + 5 x 7/5 + 2 = 67/2 boys
Now, B1 x D1 = B2 x D2
7 X 469 = 67/2 x D2
D2 = 98 days- 5. If the unit digit in the product 75? x 49 x 867 x 943 be 1, then the value of? is
Options- A. 1
- B. 3
- C. 7
- D. 9 Discuss
Correct Answer: 9
Explanation:
Let the value for ? be N
So N x 9 x 7 x 3 = a number with unit digit 1.
Clearly, the minimum value of N is 9.- 6. [(272 - 32) (124 + 176)] / (17 x 15 - 15) =?
Options- A. 0
- B. 2.25
- C. 300
- D. None of these Discuss
Correct Answer: 300
Explanation:
Given expression = [(272 - 32) (124 + 176)] / (17 x 15 - 15)
= (240 x 300 ) / 240
= 300- 7. The average of 8, 9, 12, 13, 15, 9 is
Options- A. 11
- B. 6
- C. 16
- D. 18 Discuss
Correct Answer: 11
Explanation:
Average = (8 + 9 + 12 + 13 + 15 + 9)/6
= 66 / 6
= 11- 8. A train 110 metres in length travels at 60 km/hr.In what time will it pass a man which is walking against the train at 6 km an hour?
Options- A. 71/3 seconds
- B. 6 seconds
- C. 62/3 seconds
- D. Data inadequate Discuss
Correct Answer: 6 seconds
Explanation:
? Relative speed of the train = 60 + 6 = 66 km/hr
= 66 x 5/18 m/sec = 55/3 m/sec
? Required time = 110 x (3/55) = 6 sec- 9. Four metal rods of lengths 78 cm, 104 cm, 117 cm and 169 cm are to be cut into parts of equal length. Each part must be as long as possible. What is the maximum number of pieces that can be cut?
Options- A. 27
- B. 36
- C. 43
- D. 480 Discuss
Correct Answer: 36
Explanation:
Given, length of four metal roads are 78, 104, 117 and 169 cm.
Now,
78 = 13 x 2 x 3,
104 = 13 x 2 x 2 x 2,
117 = 13 x 3 x 3,
169 = 13 x 13
Length of each piece of rod as long as possible, HCF = 13 CM
? Number of piece = 6 + 8 + 9 + 13 = 36- 10. A train travelling at 30 km an hour took 13 1/ 2 sec in passing a certain point. Find the length of the train?
Options- A. 113 metres
- B. 112 metres
- C. 112.5 metres
- D. None of these Discuss
Correct Answer: 112.5 metres
Explanation:
Speed = 30 km/hr = 30 x (5/18) = 25/3 m/sec.
? Length of the train = (25/3) x (27/2)
= 225/2 = 1121/2 metres
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