RRB Group-D Model Paper 13 with answers for online practice

Given:
Walking as 3/5 of his usual speed, a man reaches his office 10 minute late
Formula Used:
speed = distance/time
Calculation:
Let the usual speed and usual time be 's' and 't' respectively and distance remains constant in both the cases
⇒ s × t = 3s/5 × (t + 10)
⇒ st = 3st/5 + 6s
⇒ 2st/5 = 6s
⇒ t = 15 minutes
∴ required usual time = 15 minutes