Step-by-step explanation:
In statistics, the empirical rule states that for a normally distributed random variable,
- 68.27% of the data lies within one standard deviation of the mean.
- 95.45% of the data lies within two standard deviations of the mean.
- 99.73% of the data lies within three standard deviations of the mean.
In mathematical notation, as shown in the figure below (for a standard normal distribution), the empirical rule is described as

where the symbol
(the uppercase greek alphabet phi) is the cumulative density function of the normal distribution,
is the mean and
is the standard deviation of the normal distribution defined as
.
According to the empirical rule stated above, the interval that contains the prices of 99.7% of college textbooks for a normal distribution
,

Therefore, the price of 99.7% of college textbooks falls inclusively between $77 and $149.
Answer it's a closed dot on positive 2 going to the left
Step-by-step explanation:
Answer:
8
Step-by-step explanation:
because if you do it then the anwser would be 8.5 so it could be 8 or 9
Answer:
10.2 cm²
Step-by-step explanation:
regular hexagon made up of six equilateral triangles
A = (2 × 1.7) /2 × 6 = 10.2
or by the side length
A = 3√3/2 * 2² = 10.3
Answer:
see explanation
Step-by-step explanation:
Given
tan a =
= 
We require the hypotenuse h
Using Pythagoras' identity
h² = 9² + 40² = 81 + 1600 = 1681 ( take square root of both sides )
h =
= 41 , thus
sin a =
= 
cos a =
= 