We have been given that the standard deviation of a group of 20 scores is 15 and we are asked to find variance.
Since we know variance is square of standard deviation. In order to find out the variance of the given data we have to take the square of 15.

Therefore, our variance is 225.
Answer:
2,826
Step-by-step explanation:
A tenth is the first place value after the decimal point
In this case, 2,826.<u>0</u>0
To round a number to the tenths place, we look at the hundredths place
If the number is 5 or more, we add 1 to the tenths place, and leave the numbers to the right 0's
If the number is 4 or less, we keep the number as it is in the tenths place, and leave the numbers to the right 0's
In this case, the hundredths place is a 0, which is less than 4, so we keep the 0 in the tenths place, and leave the to the right 0's.
Thus, our final answer is 2,826.
(a)

or, via symmetry

____________
(b)
By the chain rule:

For polar coordinates, x = rcosθ and y = rsinθ. Since
<span>r = 3 + 2cosθ, it follows that

Differentiating with respect to theta

2/3 is the slope
____________
(c)
"</span><span>distance between the particle and the origin increases at a constant rate of 3 units per second" implies dr/dt = 3
A</span>ngle θ and r are related via <span>r = 3 + 2cosθ, so implicitly differentiating with respect to time
</span><span />
If you use slope-intercept form, Y =mx+b
m is equal to the slope,
and b is the y intercept.
Y= (1/2)x+ (-1)
or
Y = (1/2)x-1