The area of the top surface of the washer is: 160.14 square mm.
<h2>Step-by-step explanation:</h2>The top of the surface is in the shape of a annulus with a outer radius of 10 mm and a inner radius of 7 mm ( since the diameter of the hole is: 14 mm and we know that the radius is half of the diameter)
Now, we know that the area of the annulus region is given by:
where R is the outer radius and r is the inner radius.
Here we have:
Hence, we have:
Answer:
The student who weighted the rock 5 times has a 95% confidence interval of (25.2, 29.1) which is guaranteed to be more wider (less precise) than the other student who weighted the rock 20 times.
Step-by-step explanation:
What is Confidence Interval?
The confidence interval represents an interval that we can guarantee that the target variable will be within this interval for a given confidence level.
The confidence interval is given by
Where is the mean weight
is the standard deviation
is the critical value from t-table and n is the sample size.
The term is known as margin of error.
As the sample size is decreased the corresponding margin of error increases which results in wider confidence interval which means smaller precision.
The student who weighted the rock 5 times has a 95% confidence interval of (25.2, 29.1) which is guaranteed to be more wider (less precise) than the other student who weighted the rock 20 times.
We can say with 95% confidence that the true mean weight of the rock is within the interval of (25.2, 29.1).
Answer:
$ 454.86 : $33.25
Step-by-step explanation:
1.
Alex bought the new easy chair for $ 399 .
If she pays the amount in 13th month. So, she has to pay the interest of 1 month too , which is, = $
= $ 55.86
So, total amount she has to pay for the chair,
= (cost price of the chair + interest)
= $ (399 + 55.86)
= $ 454.86 (answer)
2.
If she wants to pay the amount within the 12 months, so that she doesn't have to pay the interest, her budget for that for each month will be ,
$
= $ 33. 25 (answer)