Monday, April 1, 2013

Average Formula in Math

Introduction:

Average formula in math:

The term average in math is defined as the sum of all elements in the given set divided by the total number of elements in the given set. The term average is also said to be Mean.

Formula to find average = Sum of elements / total number of elements.

Example : In math average of odd numbers between 1 to 6

=`(1+3+5)/3`

=`9/3`

=3


Example problems to find average in math :


Example 1:

To find the average of 4,7,8,9

Solution:

Sum of elements = 4 +7 +8 +9  =28

Total number of elements = 4

Therefore,

Using average formula , we get ,

Average = `28/4`

=7

Example 2:

Find average of the given set of numbers,9,8,6,4,7,5,11,4,8

Solution:

Sum of elements =  9+8+6+4+7+5+11+4+8

= 62

Total number of elements (Count all numbers) =9

Using average formula ,

Average = `62/9`

=6.88

Example 3:

The list have 5 numbers , average of these 5 numbers is 30. If we remove one of the numbers, than the average of the remaining numbers is 12. What is the number that was removed?

Solution:

Note:  Removed number is difference between sum of original 5 numbers and Sum of remaining numbers.

Therefore,

Sum of original 5 numbers = 30 *5 =150

Sum of remaining 4 numbers =  4 *12 =48

Removed number = 150 -48 =102

Example 4:

Jack drove for 2 hours at a rate of 25 miles per hour and for 1 hour at 30 miles per hour. What was his average speed for the whole journey?

Solution:

Using average speed formula =total distance / total time

Distance = speed * time

Total distance = 25 *2 +30 *1

80 and total time = 2+1 =3

Therefore , Average Speed = `80/3`

=26.66 km/h

Example 5:

The average of 4 numbers is 90 .if three of the numbers are 52 and 58,67then what is the other numbers.

Solution:

Sum of four numbers  = 4 *90 =360

Let us consider the unknown number  is X

Therefore ,

`(52 +58 +67 +x )/4`  =90

`(177+x )/4`  =90

177 +x =90 *4

177+x =360

X =360-177

=183

Therefore, fourth number is 183.

Is this topic Basic Math Formulas hard for you? Watch out for my coming posts.

Practice problem to find average using math formulas:

1. Find the average of prime numbers between 1to 10

Answer: 3.6

2) Find the average of 3,5,7,9,3?

Solution: 5.4

3) The average of 4 numbers is 12 . If three of the numbers are 4 and 2 ,3 then what is the other numbers.

Answer: 3

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