A, B and C can do one-third of a work in 15 days, 30 days and 10 days, respectively. A started the work. C joined him after 1 day and B joined them after 3 days of the beginning. For how many days did C work?

From an aeroplane just over a river, trees on the opposite bank of the river are found to be 60° and 30° respectively. If the breadth of the river is 400 m, then the height of the airplane above the river at an instant is (assume √3 = 1.732)

Raju buys 75 articles at the same price each. He sells one-third of them at a profit of 40% and 20% of the remaining at a profit of 20%. He sells the remaining articles at a loss equal to the cost price of 7 articles. What is his gain/loss per cent in the entire transaction?

A can do a piece of work in 6 days. B can do it in 9 days. With the assistance of C they completed the work in 3 days. In how many days can C alone do the work ?

After traveling 50km, a train meets with an accident and travels at 75% of its usual Speed and reaches 45 min late. Had the accident happened 10km further on it would have reached 35 min late. Find the usual Speed?