A cyclist cycles 8 km at 15 km/hr and a further 4 km at 20 km/hr. Find the average speed in km/hr. 

In one glass, milk and water are mixed in the ratio 3:5 and in another glass they are mixed in the ratio 6:1.In what ratio should the content of the two glasses be mixed together so that new mixture contains milk and water in the ratio 1:1?

In a village, each of the 60 % of families has a cow; each of the 30 % of families has a buffalo and each of the 15 % of families has both a cow and a buffalo. in all there are 96 families in the village. How many families do not have a cow or a buffalo? 

Mr. Dutta desired to deposit his retirement benefit of ₹3 lacs partly to a post office and partly to a bank at 10 % and 6 %  simple interests respectively. If his monthly interest income was ₹ 2000, then the difference of his deposits in the post office and in the bank was -

A hostel has 120 students and food supplies are for 45 days. If 30 more students come to that hostel, then in how many days will the food items be finished there?

In the given figure ΔDEF is right angle triangle, ∠G=120° and DG=12 cm , GF=10 cm then find out the value of DF.