You arrive at your school 5 minutes late if you walk with

You arrive at your school 5 minutes late if you walk with a speed of 4 km/h, but you arrive 10 minutes before the scheduled time if you walk with a speed of 5 km/h. The distance of your school from your house (in km) is

If the required distance be = x km, then

x	−	x	=	10 + 5
4	−	5	=	60

⇒	5x − 4x	=	1
	20		4

⇒	x	=	1
	20		4

⇒ x =	1	× 20 = 5 km.
	4

Second Method :
Here, S₁ = 4, t₁ = 5
S₂ = 5, t₂ = 10

Distance =	(S₁ × S₂)(t₁ + t₂)
	S₁ − S₂

=	(4 × 5)(5 + 10)
	5 − 4

= 20 ×	15	= 5 kms
	60