Discussion
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- Question
If sum of upstream and downstream speed of a boat is 82 kmph, and the boat travels 105 km. upstream in 3 hr, Find the time taken by boat to cover 126 km downstream.
Options- A. 2.8 hrs
- B. 2.7 hrs
- C. 2.6 hrs
- D. 2.5 hrs
- Correct Answer
- 2.7 hrs
ExplanationLet Speed of boat in still water = b
Let Speed of still water = w
Then we know that,
Speed of Upstream = U = boat - water
Speed of Downstream = D = boat + water
Given, U + D = 82
b - w + b + w = 82
2b = 82
=> b = 41 kmph
From the given data,
41 - w = 105/3 = 35
w = 6 kmph
Now,
b + w = 126/t
=> 41 + 6 = 126/t
=> t = 126/47 = 2.68 hrs.
- 1. ? 132 + 28 / 4 - (3)3 + 107 = (?) 2
Options- A. 2
- B. 16
- C. 256
- D. 4 Discuss
- 2. A is thrice as good a workman as B and therefore is able to finish a job in 30 days less then B. How many days will they takes to finish the job working together?
Options- A. 101/4
- B. 113/4
- C. 111/4
- D. 111/3 Discuss
- 3. Solve the following:
? / .0025 = 800
Options- A. .2
- B. .02
- C. 2000
- D. 2 Discuss
- 4. 75% of 480 = (?) x 15?
Options- A. 32
- B. 18
- C. 360
- D. None of these Discuss
- 5. Ravi can row downstream at 9 km/h and upsteam at 5 km/h. Find the speed of Ravi in still water and speed of current.
Options- A. 7 km/h and 2 km/h
- B. 8 km/h and 6 km/h
- C. 7 km/h and 3 km/h
- D. 8 km/h and 2 km/h Discuss
- 6. 56, 72, 90, 110, 132, 150
Options- A. 72
- B. 110
- C. 132
- D. 150 Discuss
- 7. The true discount on Rs. 2,562 due 4 months hence is Rs. 122. The rate percent is?
Options- A. 12
- B. 13
- C. 15
- D. 14 Discuss
- 8. Two pipes X and Y can fill a cistern in 6 and 7 min, respectively. Starting with pipe X, both the pipes are opened alternately, each for 1 min. In what time will they fill the cistern?
Options- A. 62/7 min
- B. 63/7 min
- C. 65/7 min
- D. 61/7 min Discuss
- 9. Inlet A is four times faster than inlet B to fill a tank. If A alone can fill it in 15 min, how long will it take if both the pipes are opened together?
Options- A. 10 min
- B. 12 min
- C. 15 min
- D. 14 min Discuss
- 10. In ? ABC, the median BE intersects AC at E, if BG = 6 cm, where G is the centro-id, then BE is equal to :
Options- A. 7 cm
- B. 9 cm
- C. 8 cm
- D. 10 cm Discuss
More questions
Correct Answer: 4
Explanation:
(?)2 = ?132 + 28 / 4 - (3)3 + 107
= ?169 + 7 - 27 + 107
= ?256
= ?16
= 4
Correct Answer: 111/4
Explanation:
Let A takes x and B takes 3N days to finish the job.
According to the question,
3N - N = 30
? N = 30/2 = 15 days
? B's time to complete the work = 3N
= 3 x 15 = 45 days
? (A + B)'s 1 day's work
= (1/15) + (1/45) = (3 + 1)/45 = 4/45
? (A + B) will finish the work in 4/45 days
? Required time = 4/45 = 111/4
Correct Answer: 2
Explanation:
Let k / .0025=800
Then, k = 800 x .0025
= ( 800 x 25 ) / 10000
= 2
Correct Answer: None of these
Explanation:
Let 75% of 480 = A x 15.
? (75 x 480)/100 = 15A
? A = (75 x 480)/ (100 x 15) = 24
Correct Answer: 7 km/h and 2 km/h
Explanation:
Given, downstream speed = 9 km/h
and upstream speed = 5 km/h
According to the formula
Ravi's speed in still water = (Speed downstream + Speed upstream )/2
= 1/2(9 + 5) = 14/2 = 7 km/h
and speed of current = (Speed downstream - Speed upstream)/2
= (9 - 5)/2 = 4/2 = 2 km/h.
Correct Answer: 150
Explanation:
So, 150 is wrong.
Correct Answer: 15
Explanation:
Correct Answer: 63/7 min
Explanation:
Part filled by X in 1st min and Y in the 2nd min = ( 1/6 + 1/7) = 13/42
Part filled by ( X + Y ) working alternately in 6 min = 1/2 x 13/42 x 6 =13/14
? Remaining Part = ( 1- 13/14 ) = 1/14
Now, it is the turn of X, one-sixth part is filled in 1 min.
One-fourteenth part is filled in (6 x 1/14) min = 3/7
? Required time = ( 6 + 3/7 ) = 63/7 min
Correct Answer: 12 min
Explanation:
Time taken by A to fill the tank, m = 15 min
? Time taken by B to fill the tank, n = 15 x 4 = 60
? Required time taken m x n/(m + n)
= (15 x 60)/(15 + 60) = (15 x 60)/75 = 12 min
Correct Answer: 9 cm
Explanation:
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