Answer:
3/4
Step-by-step explanation:
Answer:
a) The formula is given by mean 
the margin of error. Where the margin of error is the product between the critical value from the normal standard distribution at the confidence level selected and the standard deviation for the sample mean.
b) 
Step-by-step explanation:
Previous concepts
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
If the distribution for X is normal or if the sample size is large enough we know that the distribution for the sample mean 
is given by:
Part a
The formula is given by mean the margin of error. Where the margin of error is the product between the critical value from the normal standard distribution at the confidence level selected and the standard deviation for the sample mean.
Part b
The confidence interval for the mean is given by the following formula:
Answer: 0.6666666667
Step-by-step explanation: Simplifying
9t + -3t = 4
Combine like terms: 9t + -3t = 6t
6t = 4
Solving
6t = 4
Solving for variable 't'.
Move all terms containing t to the left, all other terms to the right.
Divide each side by '6'.
t = 0.6666666667
Simplifying
t = 0.6666666667
Anything more or less than 1 would result in a different outcome, and anything times 1 results in itself.
Answer:
x = √30
Step-by-step explanation:
From small triangle BDC:
using Pythagorean theorem
CB² = BD² + DC²
x² = BD² + 3²
Fron triangles BDC and ADB.
ΔBDC has long leg BD and short leg DC.
ΔADB has long leg AD and shirt leg BD.
AD : BD = BD : DC
7 : BD = BD : 3
7*3 = BD*BD
BD² = 7*3 = 21
x² = BD² + 3² = 21+9 = 30
x² = 30
x = √30
