Problem Solving

7.51 8.22 7.86 8.36
8.09 7.83 8.30 8.01
7.73 8.25 7.96 8.53

A vending machine is designed to dispense 8 ounces of coffee into a cup. After a test that recorded the number of ounces of coffee in each of 1000 cups dispensed by the vending machine, the 12 listed amounts, in ounces, were selected from the data. If the 1000 recorded amounts have a mean of 8.1 ounces and a standard deviation of 0.3 ounce, how many of the 12 listed amounts are within 1.5 standard deviations of the mean?

A> 4
B>6
C>9
D>10
E>11

OA is E

arbiter wrote:7.51 8.22 7.86 8.36
8.09 7.83 8.30 8.01
7.73 8.25 7.96 8.53

A vending machine is designed to dispense 8 ounces of coffee into a cup. After a test that recorded the number of ounces of coffee in each of 1000 cups dispensed by the vending machine, the 12 listed amounts, in ounces, were selected from the data. If the 1000 recorded amounts have a mean of 8.1 ounces and a standard deviation of 0.3 ounce, how many of the 12 listed amounts are within 1.5 standard deviations of the mean?

A> 4
B>6
C>9
D>10
E>11

OA is E

1.5 standard deviations of the mean equal 1,5*0,3 = 0,45. You simply need to calculate the number of 12 listed amounts are within 8,1-0,45=7,55 and 8,1+0,45=8,55 inclusive. You will have 11 figures

It's 11 figures, so it's D (>10) not E (>11), no?

So it's all figures that are between 7.55 and 8.55?

It should be between 8.1 - .45 = 7.65 (not 7.55 ) and 8.1 +0.45 = 8.65

Ans . 11

OA is D,10

1.5 standard deviation = 0.45

values +/- 1.5 std = 7.56 < x < 8.55, 11 values fall within this range