
A student starting from his house walks at a
school 6 minutes late. Next day starting atspeed of 2 1 km/hour and reaches his 2
the same time he increases his speed by 1 km/hour and reaches 6 minutes early. The distance between the school and his house is

 4 km

3 1 km 2 
1 3 km 4  6 km
Correct Option: C
Distance between school and house = x km (let)
Time =  
Speed 
According to the question,
−  =  =  
5/2  7/2  60  5 
(Difference of time = 6 + 6 =12 minutes)
⇒  −  =  
5  7  5 
⇒  =  ⇒  =  
35  5  35  5 
⇒ 4x =  = 7  
5 
⇒ x =  = 1  km.  
4  4 
Second Method :
Here, S_{1} = 2  , t_{1} = 6  
2 
S_{2} = 3  , t_{2} = 6  
2 
Distance =  
S_{2} − S_{1} 
=  ×  (6 + 6)  
2  2  
  
2  2 
=  ×  
4  60 
=  = 1  km  
4  4 