Time taken to cover 9 km = | ❨ | 9 | x 60 | ❩min | = 10 min. |
54 |
Total time taken = | ❨ | 160 | + | 160 | ❩hrs. | = | 9 | hrs. |
64 | 80 | 2 |
∴ Average speed = | ❨ | 320 x | 2 | ❩km/hr | = 71.11 km/hr. |
9 |
Speed = | ❨ | 600 | ❩m/sec. |
5 x 60 |
= 2 m/sec.
Converting m/sec to km/hr (see important formulas section)
= | ❨ | 2 x | 18 | ❩ | km/hr |
5 |
= 7.2 km/hr.
Then, distance travelled on bicycle = (61 -x) km.
So, | x | + | (61 -x) | = 9 |
4 | 9 |
⟹ 9x + 4(61 -x) = 9 x 36
⟹ 5x = 80
⟹ x = 16 km.
Speed = Distance/Time
Speed = 1200/(5/3) km/hr. [We can write 1⅔ hours as 5/3 hours]
∴ Required speed = | ❨ | 1200 x | 3 | ❩km/hr | = 720 km/hr. |
5 |
Then, speed of the train = | 150 | x | = | ❨ | 3 | x | ❩kmph. |
100 | 2 |
∴ | 75 | - | 75 | = | 125 |
x | (3/2)x | 10 x 60 |
⟹ | 75 | - | 50 | = | 5 |
x | x | 24 |
⟹ x = | ❨ | 25 x24 | ❩ | = 120 kmph. |
5 |
Then, | 30 | - | 30 | = 3 |
x | 2x |
⟹ 6x = 30
⟹ x = 5 km/hr.
Then, | 120 | + | 480 | = 8 ⟹ | 1 | + | 4 | = | 1 | ....(i) |
x | y | x | y | 15 |
And, | 200 | + | 400 | = | 25 | ⟹ | 1 | + | 2 | = | 1 | ....(ii) |
x | y | 3 | x | y | 24 |
Solving (i) and (ii), we get: x = 60 and y = 80.
∴ Ratio of speeds = 60 : 80 = 3 : 4.
36 | 2 |
3 |
37 | 1 |
2 |
Then, | x | - | x | = | 40 | ⟹ 2y(y + 3) = 9x ....(i) |
y | y + 3 | 60 |
And, | x | - | x | = | 40 | ⟹ y(y - 2) = 3x ....(ii) |
y -2 | y | 60 |
On dividing (i) by (ii), we get: x = 40.
Then, | x | - | x | = 2 |
10 | 15 |
⟹ 3x - 2x = 60
⟹ x = 60 km.
Time taken to travel 60 km at 10 km/hr = | ❨ | 60 | ❩hrs | = 6 hrs. |
10 |
So, Robert started 6 hours before 2 P.M. i.e., at 8 A.M.
∴ Required speed = | ❨ | 60 | ❩kmph. | = 12 kmph. |
5 |
13 | 1 | days |
3 |
13 | 1 | days |
3 |
Explanation:
Work done by X in 8 days = | ❨ | 1 | x 8 | ❩ | = | 1 | . |
40 | 5 |
Remaining work = | ❨ | 1 - | 1 | ❩ | = | 4 | . |
5 | 5 |
Now, | 4 | work is done by Y in 16 days. |
5 |
Whole work will be done by Y in | ❨ | 16 x | 5 | ❩ | = 20 days. |
4 |
∴ X's 1 day's work = | 1 | , Y's 1 day's work = | 1 | . |
40 | 20 |
(X + Y)'s 1 day's work = | ❨ | 1 | + | 1 | ❩ | = | 3 | . |
40 | 20 | 40 |
Hence, X and Y will together complete the work in | ❨ | 40 | ❩ | = 13 | 1 | days. |
3 | 3 |
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