Question 1: describe in words the region of double-struck r3 represented by the equation: x2 + z2 ≤ 36.
question 2: here x2 + z2 ≤ 36, or equivalently x2 + z2 ≤ 6, describes the set of all points in double-struck r3 whose distance from the -axis is a

Step-by-step explanation:

1) i will asume x2 and z2 are squares here.

ok, here we only have restrictions to x and z, so y can take all the values in R.

is a circle of radius 6, you can see this if for example we set z = 0, then x goes from -6 to 6, the same if we set x = 0 then z goes from -6 to 6.

and the equation describes a circle.

So here, the region is the solid cylinder of radius 6, where the Y axis is also the axis of the cylinder.

2) you tipped the same inequality but different numbers in the right side, here i think you are saying that the inequalities describes the set of all points whose distance from the y-axis is equal or less tan 6.

irst, find the z score of a score of 80. this is given by the formula z = (x-u)/o, where x is the score, u is the mean, and o is the standard deviation. this gives

z = (80-78)/12 = 1/6 = .1667

now, find what percentile a z score of 1/6 correlates to in the normal distribution.

a z score of 1/6 = .1667 is equivalent to the 56.36th percentile of the distribution. so the probability a score is over this is 1-.5636 = .4364

the mean of a sample mean is equal to the original mean. however, the standard deviation of a sample mean is equal to the original standard deviation divided by the square root of n (sample size). so the new standard deviation is 12/sqrt(16) = 3.

the new z score is 80-78/3 = 2/3 = .667. this is equivalent to the 74.86th percentile. so the probability that the mean will be greater than this score is 1-.7486 = .2514.