Understanding Normal Distribution and Standard Deviations

What percentage of data falls within one standard deviation from the mean in a normal distribution?

• 99.7%

• 95%

• 68%

• 50%

If 68% of data lies between 23 and 27, what percentage lies above 27?

• 84%

• 68%

• 32%

• 16%

How much data lies below 21 if the mean is 25 and the standard deviation is 2?

• 5%

• 32%

• 16%

• 2.5%

What is the percentage of data that lies outside two standard deviations from the mean?

• 5%

• 2.5%

• 32%

• 16%

In a normal distribution, what percentage of data lies within three standard deviations from the mean?

• 95%

• 68%

• 100%

• 99.7%

If 99.7% of data is within three standard deviations, what percentage lies in each tail?

• 0.15%

• 0.3%

• 0.5%

• 1%

In a normally distributed dataset, what percentage of data lies above the mean?

• 50%

• 100%

• 25%

• 75%

For a dataset with a mean of 61.1 cm and a standard deviation of 1.6 cm, what percentage of data is greater than 59.5 cm?

• 84%

• 16%

• 32%

• 68%

If 400 boys are measured, how many have a head circumference less than 48 cm given a mean of 49.5 cm and a standard deviation of 1.5 cm?

• 32

• 48

• 64

• 80

What is the first step in calculating the number of boys with a head circumference less than a certain value?

• Find the mean

• Calculate the standard deviation

• Determine the percentage below the value

• Count the total number of boys