Question

In: Statistics and Probability

Suppose that the middle 68% of monthly food expenditures for a family of four fall between...

Suppose that the middle 68% of monthly food expenditures for a family of four fall between 533.21 and 685.13. Give an approximate estimate of the standard deviation of the expenditures. Assume the expenditures have a normal distribution

Solutions

Expert Solution

Using empirical rule (68 - 95 - 99.7)

Approximately 68% data falls in 1 standard deviation of the mean.

That is 68% data falls between - and +

Comparing this interval with (533.21 , 685.13) we get,

- = 533.21 and + ​​​​​​​ = 685.13

Solve these two equations for by subtracting.

+ ​​​​​​​ = 685.13

- ( - ​​​​​​​ = 533.21)

_________________

2 = 685.13 - 533.21

= 75.96

Approximate estimate of standard deviation = 75.96


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