Answer:
Yes, the two events are independent because P(NF|PB)=P(NF).
Step-by-step explanation:
The '68-95-99.7' rule says
-About 68% of values fall within one standard deviation of the mean.
-About 95% of the values fall within two standard deviations from the mean.
-Almost all of the values — about 99.7% — fall within three standard deviations from the mean.
Here 
Therefore, the probability

The required probability

Answer:
Standard deviation of a normal data distribution is a measure of data dispersion.
Step-by-step explanation:
Standard deviation is used to measure dispersion which is present around the mean data.
The value of standard deviation will never be negative.
The greater the spread, the greater the standard deviation.
Steps-
1. At first, the mean value should be discovered.
2.Then find out the square of it's distance to mean value.
3.Then total the values
4.Then divide the number of data point.
5.the square root have to be taken.
Formula-
SD=
Advantage-
It is used to measure dispersion when mean is used as measure of central tendency.
Answer:
753
Step-by-step explanation:
m^2 =700^2 +460^-2 −2(700)(460)cos78
m^2 = 490000+211600-2(700)(460)(0.207912)
m^2 = 490000+211600-133895.12889
m^2 = 567704.87111
m=753.462=753