Given:
Sample mean = 65.4
Standard deviation = 1.2
Sample size = 45
Confidence level = 99%
To find:
The confidence interval.
Solution:
The formula for confidence interval is
where, is sample mean, z* is confidence value, s is standard deviation and n is sample size.
Confidence value or z-value at 99% = 2.58
Putting the given in the above formula, we get
Therefore, the correct option is D.
The inequality should read:
Subtract 2 from all the terms:
Divide all the terms by -5 to get x by itself (note that you flip the inequality signs as you divide by a negative):
The inequality is 2 ≤ x < 8.
A closed dot represents ≤, and an open dot represents <. Since x can represent all values between 2 and 8, you will shade in between 2 and 8 on the number line. x is greater than or equal to 2, so there will be a closed dot on 2. x is less than 8, so there will be an open dot on 8.
The answer is 'number line with a closed dot on 2 and an open dot on 8 and shading in between'.