A person takes 20 minutes more to cover a certain distance by decreasing his speed by 20%. What is the time taken to cover the distance at his original speed ?

Question

নিচের অপশন গুলা দেখুন

• 1 hr 10 min
• 1 hr 20 min
• 50 min
• 1hr

Answer 1

সঠিক উত্তর হচ্ছে: op1 hr 20 min

ব্যাখ্যা:

Let the distance and original speed be 'd' km and 'k' kmph respectively.

d/0.8k - d/k = 20/60 => 5d/4k - d/k = 1/3

=> (5d - 4d)/4k = 1/3 => d = 4/3 k

Time taken to cover the distance at original speed

= d/k = 4/3 hours = 1 hour 20 minutes.