A room is 12 ¼ m long and 7w wide. The maximum length of a square tile to fill the floor of the room with whole number of it’s tiles should be_________?

A. 10 min
B. 11 min 20 sec
C. 13 min
D. 13 min 20 sec
Speed = (10 X 60/12 ) km/hr = 50 km/hr. New speed = (50 – 5) km / hr = 45 km /hr. So Time taken = ( 10/45 ) hr = ( 2/9X 60 )min 131/3 min = 13 min 20 sec.

A. 120
B. 260
C. 240
D. 220

Explanation with best method.
5 Steps
1.Data:
Train station platform= 36Sec
Standing platform = 20Sec
Speed of train = 54km/hr
2.Required:
Length of platform= x=???
3.Formula:
X+length of train/Train station platform
4.Solution: first for terms
Speed = 54 ×1000m/3600sec = 15 m/Sec.
Length of the train = (15 m/Sec × 20Sec = 300 m.
Let the length of the platform be x metres.
Now, x + 300m /36Sec= 15 m/Sec
x+300m= 15m/Sec×36Sec
x + 300m = 540m
x= 540m-300m
x = 240 m.
5.Result:
Length of platform=x=240m