Question

a part of the monthly expenditure of a family is constant and the remaining varies with the price of wheat . when the rate of wheat is Rs 250 per quintal, the total monthly expenditure is Rs 1000 and when it is Rs 240 per quintal, the total monthly expenditure of the family is Rs 980 find the total monthly expenditure of the family when the cost of wheat Rs 350 per quintal

Answer 1

let monthly expenditure is x
let family requires y quintal of wheat per month

therefore by first condition

x + 250 y = 1000 ------ ( 1 )

and with second condition

x + 240 y = 980 ------- ( 2)

subtracting eq 2 from eq 1 we get

10 y =20

y = 2 quintals

therefore family needs 2 quintals of wheat per month

putting y =2 in eq 1 we get

x = 500

therefore fix expenditures are 500

therefore when cost of wheat is 350

expenditure = 500 + 2 × 350

= 500 + 700 = 1200