Question

a data set with 5 numbers in it has a standard deviation of about 79 and a mean of 60. Four of the numbers are 10, 20, 30, and 40. What could the 5th number be?

Answer 1

100

Step-by-step explanation:

Total of 5 numbers = mean x 5 = 5 x 60= 300

Sum of 4 numbers= 10+20+30+40=100

So 5th number = 300 - 200 = 100

Answer 2

Answer: 200

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Step-by-step explanation:

x = missing value

The data set is {10,20,30,40,x}

The sum of the values is 10+20+30+40+x which simplifies to 100+x

Divide this sum over the sample size n = 5 to compute the mean. Set this equal to 60 since we want the mean to be this.

mean = (sum of the values)/(sample size)

60 = (100+x)/5

60*5 = 100+x

300 = 100+x

x = 300-100

x = 200 is the missing value

Therefore, the mean of the set {10,20,30,40,200} is 60.

If you were to find the sample standard deviation that set, then it's roughly 79.057