E.g. 18: y varies directly as x and when x = 6, y = 24. What is the value of y, when x = 5?

Ex 19 : The value of a diamond varies directly as the square of its weight. If a diamond weighing 1.5 gms has a value of Rs. 9,000, what will be the value of a diamond weighing 2.5 gms?

Ex 23 . The number of four wheelers sold in a year vary inversely with the number of two wheelers sold in that year. If 4000 four wheelers were sold in one particular year, 21000 two wheelers were sold that year. How many two wheelers were sold in a year, when 6000 four wheelers were sold?

Ex 24 The cost per kg of rice varies inversely with the square of the quantity of rice produced in a year. When 7 million tons of rice was produced, its cost was Rs. 36/kg. How much was the production in the year when the cost of rice was Rs. 49/kg? x varies directly with y as well as z. When x = 2 and y = 3, z = 5. What is the value of x when y = 9 and z = 15? 

Ans

18 - 20

19- 25000

23-14000

24-6 million tonnes