68-95-99.7 Rule So
LEARNING OBJECTIVE: Identify the percent of data that is between two values
using a given standard deviation, mean, and the 68-95-99.7 rule.
68
At a nearby frozen yogurt shop, the mean cost of a pint of frozen yogurt is $1.50
with a standard deviation of $0.10.
Assuming the data is normally distributed, approximately what percent of
customers are willing to pay between $1.30 and $1.70 for a pint of frozen
yogurt?
T

9514 1404 393

  95%

Step-by-step explanation:

The given limits differ from the mean by ...

  1.30 -1.50 = -0.20

  1.70 -1.50 = 0.20

These values are 2 × the standard deviation of 0.10. The 68-95-99.7 rule tells you that 95% of the population lies within 2 standard deviations of the mean.

For this question, that means 95% of customers are willing to pay between $1.30 and $1.70.

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so: