Answer: 3 : 4

Explanation:
Let the speed of the train be x km/hr and that of the car be y 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.

Answer: 35 km/hr

Explanation:
Time taken = 1 hr 40 min 48 sec = 1 hr 40 4/5 min = 1 51/75 hrs = 126/75 hrs.

Let the actual speed be x km/hr.
Then, 5/7 x * 126/75 = 42

x = (42 x 7 x 75) / (5 x 126 )   = 35 km/hr.
 

Answer: 224 km

Explanation:

Answer: 120 kmph

Explanation:

Answer: 40

Explanation:
The average speed ‘v’, when a man travels two same distance with different speeds ‘v1’ and ‘v2’ is:
v = (2*v1*v2) / (v1 + v2)
In the above problem, v1 = 30 and v2 = 60
Therefore, v = (2*30*60)/(30 + 60) = 3600/90
v = 40

Answer: 3.6 km

Explanation:
Average speed of Mayur = (2*2*3)/(2 + 3) = 2.4 km/hr
If d is he distance between the school and Mayur’s home, then total distance walked by Mayur = 2d, and the total time taken is 3 hours
2.4 = 2d/3
7.2 = 2d
d = 3.6 km

Answer: 0.78 minutes

Explanation:
Total distance = addition of length of the two trains = 140 + 120 = 260 metres
As the two trains are travelling in the same direction, their relative speed is:
v = | v1 – v2 | = | 40 – 60 | = 20 km/hr = 20*1000/60 = 1000/3 metres/min
t = 260/ 1000*3
t = 0.78 minutes

Answer: 21.12s

Explanation:
Area of the cicular ground = 2464m2 = pr2
r = 28 m
Circumference = 2* p*r = 2*p*28 = 175.93 m = distance covered by the athlete
Speed of the athlete = 30 km/hr = 8.33 m/s
Time = distance/speed = 175.93/8.33 = 21.12s

Answer: 15 minutes

Explanation:
As the squirrel climbs 5 m in one minute and slips 2 metres in the next minute, it climbs 3 metres in 2 minute
To climb 26 metres, the time required is:
The squirrel will climb (26 – 5) = 21 metres = 7 * 3 metres in 7 * 2 = 14 minutes
Also, the last 5 metres it climbs in another 1 minute
Hence, total time required = 14 + 1 = 15 minutes

Answer: 40 km

Explanation:
x = 7 km/hr ; y = 3 km/hr
Ds = 10 km/hr ; Us = 4 km/hr
Distance (d) is same. Therefore, if time taken for downstream is t hours, the time for upstream is (t + 6) hours.
10*t = 4*(t + 6)
6t = 24 ; t = 4 hours
d = 10*4 = 40 km