9.05 Z-scores
Interactive practice questions
The heights of $500$500 boys are found to approximately follow a normal distribution, with a mean height of $145$145 cm and a standard deviation of $11$11 cm. Find the number of boys with heights between:
$134$134 cm and $156$156 cm
$112$112 cm and $178$178 cm (to the nearest whole number)
The following figure shows the approximate percentage of scores lying within various standard deviations from the mean of a normal distribution. A set of scores is found to follow such a distribution, where the mean score is $92$92 and standard deviation is $20$20. Calculate each of the following using the given values. Find the percentage of scores between:
The number of biscuits in a box is approximately normally distributed with mean $30$30 and standard deviation of $3$3.
The times for runners to complete a $100$100 m race is approximately normally distributed with mean $14$14 seconds and standard deviation of $1.9$1.9 seconds.