Question

A person buys q1, q2, q3 and q4 units of four goods whose prices per unit are, re- spectively, $1, $2, $3 and $4. What is the total expenditure? What will be the total expenditure if the prices change to $4, $3, $2 and $1 per unit respectively?

Answer 1

`\[q1 + 2q2+3q3+4q4\]`

`\[4q1 + 3q2+2q3+q4\]`

Explanation:

Quantity of good1 = q1

Unit price of good1 = $1

Quantity of good2 = q2

Unit price of good2 = $2

Quantity of good3 = q3

Unit price of good3 = $3

Quantity of good4 = q4

Unit price of good4 = $4

Total expenditure =
`\[\sum (quantity*unitprice)\]`

=
`\[q1 + 2q2+3q3+4q4\]`

If the prices change to $4, $3, $2 and $1 per unit respectively, total expenditure =
`\[4q1 + 3q2+2q3+q4\]`