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Answer:
The 90% confidence interval for the mean time required by all college graduates is between 5.36 years and 5.44 years.
Step-by-step explanation:
We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of .
So it is z with a pvalue of , so
Now, find the margin of error M as such
In which is the standard deviation of the population and n is the size of the sample.
The lower end of the interval is the sample mean subtracted by M. So it is 5.4 - 0.04 = 5.36 years.
The upper end of the interval is the sample mean added to M. So it is 5.4 + 0.04 = 5.44 years.
The 90% confidence interval for the mean time required by all college graduates is between 5.36 years and 5.44 years.
Answer:
There are 26 purple marbles in the bag.
Step-by-step explanation:
Firstly, you have to make an expression in terms of x where x represent red marbles. Given that the question says purple marbles is 2 more than 3 times the number of red marbles. So the expression is :
Let red marbles = x,
Next, given that the total marbles in the bag is 34 so you have to add both marbles together and solve the value of x :
Lastly, you have to substitute the value of x into the expression of purple marbles :
Let x = 8,