In a random sample of five mobile devices, the mean repair cost was $90.00 and the standard deviation was $14.00. Assume the
1 answer:
Answer:
The correct option is;
B. With 95 percent confidence, it can be said that the repair cost is between the bounds of the confidence interval
Step-by-step explanation:
Here we have the formula for confidence interval, CI given as follows;
Where:
= Sample mean = $90.00
s = Sample standard deviation = $14.00
n = Sample size = 5
t = z value for the confidence level = 2.7764 from z-score relations
Plugging in the values, we have;
Which gives the CI as 72.6167 to 107.38.
You might be interested in
Since the angle is in radians, then s = rθ.
Question 1
probability between 2.8 and 3.3
The graph of the normal distribution is shown in the diagram below. We first need to standardise the value of X=2.8 and value X=3.3. Standardising X is just another word for finding z-score
z-score for X = 2.8
(the negative answer shows the position of X = 2.8 on the left of mean which has z-score of 0)
z-score for X = 3.3
The probability of the value between z=-0.73 and z=0.49 is given by
P(Z<0.49) - P(Z<-0.73)
P(Z<0.49) = 0.9879
P(Z< -0.73) = 0.2327 (if you only have z-table that read to the left of positive value z, read the value of Z<0.73 then subtract answer from one)
A screenshot of z-table that allows reading of negative value is shown on the second diagram
P(Z<0.49) - P(Z<-0.73) = 0.9879 - 0.2327 = 0.7552 = 75.52%
Question 2
Probability between X=2.11 and X=3.5
z-score for X=2.11
z-score for X=3.5
the probability of P(Z<-2.41) < z < P(Z<0.98) is given by
P(Z<0.98) - P(Z<-2.41) = 0.8365 - 0.0080 = 0.8285 = 82.85%
Question 3
Probability less than X=2.96
z-score of X=2.96
P(Z<-0.34) = 0.3669 = 36.69%
Question 4
Probability more than X=3.4
P(Z>0.73) = 1 - P(Z<0.73) = 1-0.7673=0.2327 = 23.27%
probability between 2.8 and 3.3
The graph of the normal distribution is shown in the diagram below. We first need to standardise the value of X=2.8 and value X=3.3. Standardising X is just another word for finding z-score
z-score for X = 2.8
z-score for X = 3.3
The probability of the value between z=-0.73 and z=0.49 is given by
P(Z<0.49) - P(Z<-0.73)
P(Z<0.49) = 0.9879
P(Z< -0.73) = 0.2327 (if you only have z-table that read to the left of positive value z, read the value of Z<0.73 then subtract answer from one)
A screenshot of z-table that allows reading of negative value is shown on the second diagram
P(Z<0.49) - P(Z<-0.73) = 0.9879 - 0.2327 = 0.7552 = 75.52%
Question 2
Probability between X=2.11 and X=3.5
z-score for X=2.11
z-score for X=3.5
the probability of P(Z<-2.41) < z < P(Z<0.98) is given by
P(Z<0.98) - P(Z<-2.41) = 0.8365 - 0.0080 = 0.8285 = 82.85%
Question 3
Probability less than X=2.96
z-score of X=2.96
P(Z<-0.34) = 0.3669 = 36.69%
Question 4
Probability more than X=3.4
P(Z>0.73) = 1 - P(Z<0.73) = 1-0.7673=0.2327 = 23.27%