Answer: Option D

Explanation:
Speed of the truck = Distance/Time=550/1=550 meters/minute
Speed of the train = Distance/Time=33/45 km/minute = 33000/45 meters/minut
Speed of the truck/Speed of the train = 550/(33000/45) = (550 × 45)/33000 = (55 × 45)/3300
= (11 × 45)/660 = (11×9)/132 = 9/12 = 34  
Hence, Speed of the truck : Speed of the train = 3 : 4

Answer: Option B

Explanation:
The man in the train notices that he can count 21 telephone posts in one minute.
Number of gaps between 21 posts are 20 and Two posts are 50 metres apart.
It means 20 x 50 meters are covered in 1 minute.
Distance = 20×50 meter = (20×50)/1000 km = 1 km
Time = 1 minute = 1/60hour
Speed = Distance/Time=1(1/60) = 60 km/hr

Answer: Option A

Explanation:
Method : 1
If a car covers a certain distance atxkmph and an equal distance at y kmph,
the average speed of the whole journey = 2xy/x+y kmph.
By using the same formula, we can find out the average speed quickly
Speed with which he travels from A to B = x = 40 km/hr
Speed with which he travels from B to A = x = 40×(100+50)/100 = 60 km/hr
average speed = (2×40×60)/(40+60) = 48 km/hr

Assume that distance from A to B =  x km
Speed with which he travels from A to B = x = 40 km/hr
Time to travel from A to B = distance/speed = x/40 hr
Speed with which he travels from B to A = 40×(100+50)/100 = 60 km/hr
Time to travel from B to A = distance/speed = x/60
Total distance traveled = x+x = 2x
Total time taken = x/40 + x/60
Average speed = Total distance traveled/Total time taken = 2x/(x/44)+(x/60)
= 2/[(1/60)+(1/40)] = (2×2400)/(40+60) = 2×24 = 48 km/hr

Answer: Option B

Explanation:
Time taken to travel 600 km = Distance/Speed =600/100 = 6 hour
Now we need to find out the number of stops in the 600 km travel.
Given that train stops after every 75 km.
600/75 = 8

It means train stops 7 times before 600 km and 1 time just after 600 km. Hence we need
to take only 7 stops into consideration for the 600 km travel.
Hence, total stopping time in the 600 km travel = 7 x 3 = 21 minutes
Total time needed to reach the destination = 6 hours + 21 minutes = 6 hrs 21 min

Answer: Option A

Explanation:
Speed = 5 km/hr
Time = 15 minutes = 1/4 hour
Length of the bridge = Distance Travelled by the man = Speed × Time = 5×1/4 km
= 5 × 1/4 × 1000 metre=1250 metre 

Answer: Option B

Explanation:

Assume that they meet x hours after 8 a.m. 
Then,train1,starting from A , travelling towards B, travels x hours till the trains meet
⇒Distance travelled by train1 in x hours = Speed ×Time = 60x

Then, train2, starting from B , travelling towards A, travels (x-1) hours till the trains meet
⇒Distance travelled by train2 in (x-1) hours = Speed ×Time = 75(x-1)
Total distance travelled = Distance travelled by train1 + Distance travelled by train2
=> 330 = 60x + 75(x-1)
=> 12x + 15(x-1) = 66
=> 12x + 15x - 15 = 66
=> 27x = 66 + 15 = 81
=> 3x = 9
=> x = 3
Hence the trains meet 3 hours after 8 a.m., i.e. at 11 a.m.

Answer: Option B

Explanation:
Speed = Distance/Time = 200/24 m/s=200/24 × 18/5 km/hr 
= 40×34 km/hr = 10×3 km/hr = 30 km/hr 

Answer: Option A

Explanation:

Speed of the sound = 1100 ft/s
Time = 11/5 second
Distance = Speed × Time = 1100 ×11/5 = 220 × 11= 2420 ft

Answer: Option A

Explanation:
Given that distance travelled in 1st hour = 35 km
and speed of the bus increases by 2 km after every one hour
Hence distance travelled in 2nd hour = 37 km
Hence distance travelled in 3rd hour = 39 km
..
Total Distance Travelled = [35 + 37 + 39 + ... (12 terms)]
This is an Arithmetic Progression(AP) with
first term, a=35, number of terms,n = 12 and common difference, d=2.

The sequence a , (a + d), (a + 2d), (a + 3d), (a + 4d), . . . 
is called an Arithmetic Progression(AP)
where a is the first term and d is the common difference of the AP
Sum of the first n terms of an Arithmetic Progression(AP),
S_n = n/2[2a+(n−1)d]
where n = number of terms
Hence, [35+37+39+... (12 terms)]
= S12 = 122[2 × 35 +(12 − 1)2] 
= 6[70 + 22] = 6 × 92 = 552
Hence the total distance travelled = 552 km

Answer: Option A

Explanation:
distance = 600 meter
time = 5 minutes = 5 x 60 seconds = 300 seconds
Speed = distance/time = 600/300 = 2m/s
= 2×185 km/hr = 365 km/hr = 7.2 km/hr