5. Who is the father of Geometry?
Sol: (d) Euclid
6. A milkman mixes 20 liters of water with 80 liters of milk. After selling one-fourth of this mixture he adds water to replenish the quantity that he has sold. What is the current proportion of water to milk?
Sol: (b) Total Mixture = 20 + 80 = 100 litres
; Water Milk = 40 : 60=2 : 3
7. In the new budget, the price of a petrol rose by 10%, the percent by which one must reduce the consumption so that the expenditure does not increase is :
9. If 2x + 3y = 24 and 2x – 3y = 12, then the value of xy is _______ .