Question

The average marks of four subjects is 120. If 33 was misread as 13 during the calculation what will be the correct average?

Answer 1

Given:

The average marks of four subjects are 120.

To find:

The correct average of marks if 33 was misread as 13 during the calculation.

Solution:

The correct average of marks is 75.

To answer this question, we will follow the following steps:

As given, we have,

Average of four subjects = 120

This means

$\frac{sum \: of \: marks \: of \: three \: subjects \: + 13}{4} = 120$

So,

$sum \: of \: marks \: of \: three \: subjects + 13 = 480$

$sum \: of \: marks \: of \: three \: subjects = 480 - 13 = 467 \: \: (i)$

Now,

as given, 33 was misread as 13

So,

The actual average of marks

$= \frac{sum \: of \: marks \:of \: three \: subjects \: + 33 }{4}$

$= \frac{267 + 33}{4}$

$= \frac{300}{4}$

$= 75$

Hence, if 33 was misread as 13 during the calculation, the correct average of marks will be 75.

Answer 2

Answer:

Average of marks of 4 subjects = 500/4 = 125  

Step-by-step explanation:

Given data

The average marks of four subjects = 120

and 33 is misread as 13 during the calculations

Here we need to find the correct average

⇒ average marks of 4 subjects =  sum of the 4 subject marks / 4 = 120

⇒ sum of the marks of 4 subjects = 120 × 4 = 480

here 33 is misread as 13

⇒ subtract "13" and add "33" to the sum of the marks of 4 subjects

⇒ 480 - 13 + 33 = 500

average marks of 4 subjects = 500/4 = 125