Question
A boat moves downstream at 45 km/h, which is (25/10) m/s
faster than its upstream speed. If it covers (D + 24) km downstream and (D - 36) km upstream in a total of 8.5 hours, find the approximate value of ‘D’.Solution
ATQ, Upstream speed = 45 - (25/10) × (18/5) = 45 - 9 = 36 km/h Multiply throughout by LCM of 45 and 36 → LCM = 180 Or, 4 × (D + 24) + 5 × (D - 36) = 8.5 × 180 Or, 4D + 96 + 5D - 180 = 1530 Or, 9D - 84 = 1530 Or, 9D = 1614 Or, D = 179.33 Approximate value: D ≈ 179
A man first travels 140 km at 70 km/hr and next 140 km at 35 km/hr. The average speed for the first 280 km of his travelling is:
Harsh and Dev planned to meet each other. Dev starts to travel from point A to B at the speed of 42 kmph at 10:00 AM and Harsh starts from point B to A...
The average speed of a bus is 2/3 of the average speed of a car which covers 1800 km in 20 hrs. What is the average speed of the bus?
A can complete a task in 20 days, and B can complete the same task in 25 days. If A works for 6 days and then leaves, in how many days will B complete t...
Traveling at his normal speed, a man covers the distance to his destination in 15 hours. If he reduces his speed by (1/5) , he covers 75 km less in the ...
A train travels from Station A to Station B at a speed of 60 km/h and returns from Station B to Station A at a speed of 40 km/h. Find the average speed ...
A tiger chases a deer that initially has a 96-meter head start, running away at 4 m/s, while the tiger pursues at 7 m/s. How long does it take for the t...
A boy goes to school at 8 km/Hr and return at a speed of 7 km/hr. If he takes 15 hrs in all. Find the distance from his village to school?
A 200-meter long truck is traveling at a speed of 180 km/hr, and it takes 10 seconds to cross a toll plaza. Now, if another truck, which is 180 meters s...
When the bus moves at 3/4 of its usual speed, it is 20 minutes late. What is its usual time to cover the journey?Â
Relevant for Exams:
