The length of a plot is five times its breadth. A playground measuring 245 square metres occupies half of the total area of the plot. What is the length of the plot?

The mean of 9 observations is 16. One more observation is included and the new mean becomes 17. The 10th observation is

Rajesh covers the distance by car driving at 60 kmph and returns back to the starting point riding on a scooter at 45 kmph. What is his average speed?

By selling an article for Rs. 600 there is a profit of 20%. What is the cost price of the article?

A loan is to be returned in two equal yearly instalments. If the rate of interest is 10% p.a., compounded annually, and each instalment is ₹5,808, then the total interest charged in this scheme is:

Ratio of speed of boat in down stream and speed of stream is 9:1, if speed of current is 3 km per  hr, then find distance travelled(in km) upstream in 5 hours.

Find the square root of (272² - 128²).

The average score of 14 students was calculated as 71. But later it was found that marks of one student were recorded as 42 instead of 56 and as 74 instead of 32 of the other. Correct average?