Question

Nisha secured 73,86,78 and 75 marks in four tests. What is the least number of point she can secure in her next test if she is to have an average of 80?

Answer 1

$average = \frac{sum \: of \: all \: observation}{total \: observation}$
$80 = \frac{73 + 86 + 78 + 75 + x}{5}$
$5 \times 80 = 312 + x$
$400 - 312 = x$
$x = 88$