Question

The time required to finish a test in normally distributed with a mean of 40 minutes and a standard deviation of 8 minutes. What is the probability that a student chosen at random will finish the test in more than 56 minutes?



84%


2%


34%


16%

Answer 1

what do you have to find a solution with?

Answer 2

do you know the empirical rule?

Answer 3

no I don't know it

Answer 4

you have some studying to do then .... look up the empirical rule and let me know what you get

Answer 5

okay I looked it up

Answer 6

what does it say ...

Answer 7

In statistics, the so-called 68–95–99.7 rule is a shorthand used to remember the percentage of values that lie within a band around the mean in a normal distribution with a width of one, two and three standard deviations, respectively; more accurately, 68.27%, 95.45% and 99.73% of the values lie within one, two and three standard deviations of the mean, respectively. In mathematical notation, these facts can be expressed as follows, where x is an observation from a normally distributed random variable, μ is the mean of the distribution, and σ is its standard deviation:

Answer 8

copy paste eh, at least you found it :)

now, we need to know how many standard deviation are between the mean, and the desired value.

we start by finding the difference between them.

what is the difference?

Answer 9

I got it form here, I just need to know how to start it out. Thank you so much for your help!

Answer 10

ok, if you need more help on it, just let me know.