A train is 125 m long. If the train takes 30 seconds to cross a tree by the railway line, then the speed of the train is:

28 men can complete a piece of work in 15 days and 15 women can completed the same piece of work in 24 days. What is the respective ratio between the amount of work done by 30 men in 1 day and the amount of work done by 18 women in 1 days? 

A man sold 18 cots for Rs.16800, gaining there by the cost price of 3 cots. The cost price of a cot is 

If (a + b):(b + c):(c + a) = 7:6:5 and a + b + c = 27, then what will be the value of 1/a: 1/b :1/c?

The average of 19 numbers is 24. If each number is multiplied by 3, what is the new average?

A certain sum increases by 50 % in 5 years. Three sums x, y and z are lent for 10, 15 and 20 years respectively. If amount on each sum is equal, then find the ratio of x, y and z. 

30 pens and 75 pencils altogether were purchased for Rs .510. If the average price of a pencil was Rs. 2, what was the average price of a pen? 

X, Y and Z can do a piece of work in 46 days, 92 days and 23 days, respectively. X started the work. Y joined him after 2 days. If Z joined them after 8 days from the beginning, then for how many days did X work?