PQR is an equilateral triangle whose side is 10 cm . What is the value (in cm) of the inradius of triangle PQR ?

If 2x + 3y - 5z = 18 , 3x + 2y + z = 29 and x + y + 3z = 17 , then what is the value of xy + yz + zx ? 

Cost of 8 pencils, 5 pens and 3 erasers is Rs.111. Cost of 9 pencils, 6 pens and 5 erasers is Rs.130. Cost of 16 pencils, 11 pens and 3 erases is Rs. 221 What is the Cost (in Rs) of 39 pencil , 26 pens and 13 erasers ?

36 people working 8 hours a day can do 3 units of work in 12 days. How many persons are required to do 5 units of that work in 16 days. If they work for 6 hours a day?

Excluding stoppages, the speed of a train is 120 kmph and including stoppage, it is 50 kmph. For how many minutes does the train stop per hour?

A train travels 40% faster than a car. Both start from Point A at the same time and reach point B, 140 km away at the same time. On the way the train takes 25 minutes for stopping at the stations. What is the speed (in km/hr) of the train?

The ratio of the efficiencies of A. B and C is 7: 5: 4. Working together, they can finish a work in 35 days. A and B work together for 28 days. The remaining work will be completed (in days) by C alone: