Question

Rohit scored 92, 85, and 78 in three Maths tests. How much should he score in the 4th test so as to get an average of 87 in four Maths test?

• A. 92 marks
• B. 91 marks
• C. 95 marks
• D. 93 marks

Answer 1

The correct option is D 93 marks

Let, $x$ be the marks of the fourth test.

we know that,
$\text{Average}=\frac{\text{Sum of observations}}{\text{Total number of observations}}$

$\therefore \text{Average of marks}=\frac{\text{Sum of Marks in tests}}{\text{Number of tests}}$
$\Rightarrow$87 = $\frac{x+92+85+78}{4}$
$\Rightarrow$ $87\times 4$ = $x$ + 92 + 85 + 78
$\Rightarrow$ 348 = $x$ + 92 + 85 +78
$\Rightarrow$ 348 = $x$ + 255
$\Rightarrow$ $x$ = 348 - 255
$\Rightarrow$ $x$ = 93

Thus, Rohit should obtain 93 marks to get the average of 87 in four Mathematics tests.