The average cost of a book is $ A.
( i ) The total cost of 8 books is $ 36.
Find the value of A.
( 1 )
( ii ) One of the 8 books is removed.
The cost of this book is $ 6.60.
Find the new value of A.
( 2 )
( iii ) The total cost of x books is $ y.
Write an expression for A in terms of x and y.
( 1 )
( iv ) One of the x books is removed.
The cost of this book is $ 7.
Write an expression for A in terms of x and y.
( i )
Total cost of 8 books = $36
Average cost of a book = Total cost / Number of books
A = 36 / 8
A = $4.50
( ii )
New total cost of 7 books = $36 - $6.60 = $29.40
New average cost of a book = New total cost / Number of books
New A = 29.40 / 7
New A = $4.20
( iii )
A = y / x
( iv )
New total cost of x-1 books = y - $7
New A = (y - 7) / (x - 1)