Interactive practice questions
The operating times of phone batteries are approximately normally distributed with mean $34$34 hours and a standard deviation of $4$4 hours. Answer the following questions using your calculator:
Approximately what percentage of batteries last between $33$33 and $38$38 hours?
Round your answer to the nearest percent.
Approximately what percentage of batteries last between $28$28 hours and $41$41 hours?
Any battery that lasts less than $23$23 hours is deemed faulty. If a company manufactured $51000$51000 batteries, approximately how many batteries would they be able to sell? Round your answer to the nearest integer.
The height of sunflowers is approximately normally distributed, with a mean height of $1.6$1.6 m and a standard deviation of $8$8 cm.
In the Maths Methods course at Winter Heights High, the mean mark for the year was $62%$62% and the standard deviation was $13%$13%.
The length of the tail of a domestic cat is normally distributed with a mean of $25$25 cm and a standard deviation of $2.2$2.2 cm.
Use the capabilities of your CAS calculator to answer the following, rounding your answers to three decimal places: