A student takes 1.25 hours to travel from home to school at a speed of 4 km/h. By what percentage should he increase his speed to reduce the time by 25% to cover the same distance from school to home?
Answer & explanation
Correct answer: option 1
Speed of the student = 4 km/hr
Distance = Speed × Time
Distance between home and school = 4 × 1.25 = 5 km
According to question ,
New time = 1.25 × \(\frac{3}{4}\) =\(\frac{15}{16}\) hr
New speed = \(\frac{5× 16 }{15}\)
= \(\frac{ 16 }{3}\) km/h
Now ,
Ratio of original speed to new speed = 4 : 16/3 = 3 : 4
Let original speed = 3 and New speed = 4
Speed increased by = 4 - 3 = 1
∴ Speed increased by (in %) = \(\frac{1 }{3}\) × 100 = 33\(\frac{1 }{3}\)%