Question Video: Using the Mean to Find a Missing Value in a Set of Data | Nagwa Question Video: Using the Mean to Find a Missing Value in a Set of Data | Nagwa

# Question Video: Using the Mean to Find a Missing Value in a Set of Data Mathematics • First Year of Preparatory School

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Noah has the following data: 18, π, 11, 15. If the mean is 13, find the value of π.

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### Video Transcript

Noah has the following data: 18, π, 11, 15. If the mean is 13, find the value of π.

Noahβs data set contains four values, three of which are known and one of which is unknown. We are also told that the mean of these values is 13. The mean of a data set is calculated by finding the sum of all the values in the data set and dividing it by how many values there are.

We know that the mean is 13 and the number of values is four. So we can form an equation. 13 is equal to the sum of all the values divided by four. Multiplying both sides of this equation by four, we find that the sum of all the values is 52. Weβre now able to form an equation that will enable us to determine the value of π. Summing the four values gives 18 plus π plus 11 plus 15, and we can equate this expression to 52. Simplifying on the left-hand side gives π plus 44 equals 52. And then subtracting 44 from each side gives π equals eight.

So, by first using the definition of the mean to find the sum of all the values in the data set, weβve found that the missing value, π, is eight.

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