Question

The average of four numbers is 36. Three of them are 34, 40 and 38. Find the fourth number

Answer 1

To find: fourth number

Given data : The average of four numbers is $36$.

                     Three numbers are : $34, 40$ and $38$  

Solution :

• Average is the arithmetic mean.

• It is the ratio of sum of all the numbers given in data to the total number of observations.

• Formula: $Average =\frac{\text { sum of all the observations }}{\text { total of observations }}$

• Here, Average = $36$  

• Total number of observations = $4$
• Let , fourth number be $x$

• Then by substituting values in above formula, we find $x$

      $Average =\frac{\text { sum of all the observations }}{\text { total of observations }}$

                $36 = \frac{34 + 40 + 38 + x}{4} \\36 = \frac{112}{4} \\x = 28$

Hence ,fourth number is $28$.

Answer 2

Answer:

The fourth number is $32$.  

Step-by-step explanation:

Given : The average of four numbers = $36$

           Three numbers = $34, 40, 38$

To find : Find the fourth number

Solution :

• It is given that the average of four numbers = $36$  

                  Three numbers = $34, 40, 38$

• We have to find the fourth number.
• Let, $x$ be the fourth number.
• We know that average is defined as the ratio of sum of set of numbers to the total count of numbers of a set.
• According to the definition of average, the equation becomes

     $\frac{34+40+38+x}{4} =36$

     ∴ $112+x=36*4$

      ∴ $112+x=144$

              ∴ $x=144-112$

              ∴ $x=32$

• ∴ The fourth number is $32$.