Question

Find the difference between the arithmetic means of all even and odd numbers between 60 and 70.
(2 marks)

Answer 1

The even numbers between 60 and 70 are 62, 64, 66 and 68.
The odd numbers between 60 and 70 are 61, 63, 65, 67 and 69.
(0.5 mark)

The arithmetic mean of even numbers between 60 and 70 is
$=\frac{62+64+66+68}{4}$
$=\frac{260}{4}$
$=65$
(0.5 mark)

The arithmetic mean of odd numbers between 60 and 70 is
$=\frac{61+63+65+67+69}{5}$
$=\frac{325}{5}$
$=65$
(0.5 mark)

$\therefore$ Required difference = 65 - 65 = 0
(0.5 mark)