The heights of a random sample of 50 college students showed a sample mean of 174.5 centimeters and a sample standard deviation of 6.9 centimeters. construct a 98% confidence interval for the mean height of all college students.

Step-by-step explanation:

We want to construct a 98% confidence interval for the mean height of all college students.

Number of sample, n = 450

Mean, u = 174.5 centimeters

Standard deviation, s = 6.9 centimeters

For a confidence level of 98%, the corresponding z value is 2.33. This is determined from the normal distribution table.

We will apply the formula

Confidence interval

= mean ± z × standard deviation/√n

It becomes

174.5 ± 2.33 × 6.9/√450

= 174.5 ± 2.33 × 0.325

= 174.5 ± 0.757

The lower end of the confidence interval is 174.5 - 0.757 =173.743

The upper end of the confidence interval is 174.5 + 0.757 =175.257

Therefore, with 98% confidence interval, the mean height of all college students is between 173.743 centimeters and 175.257 centimeters.

{x = -1/2 ,   y = -1

step-by-step explanation:

solve the following system:

{2 x + y = -2

{10 x - 3 y = -2

in the first equation, look to solve for y:

{2 x + y = -2

{10 x - 3 y = -2

subtract 2 x from both sides:

{y = -2 x - 2

{10 x - 3 y = -2

substitute y = -2 x - 2 into the second equation:

{y = -2 x - 2

{10 x - 3 (-2 x - 2) = -2

10 x - 3 (-2 x - 2) = (6 x + 6) + 10 x = 16 x + 6:

{y = -2 x - 2

{16 x + 6 = -2

in the second equation, look to solve for x:

{y = -2 x - 2

{16 x + 6 = -2

subtract 6 from both sides:

{y = -2 x - 2

{16 x = -8

divide both sides by 16:

{y = -2 x - 2

{x = -1/2

substitute x = -1/2 into the first equation:

{y = -1

{x = -1/2

collect results in alphabetical order:

answer:   {x = -1/2 ,   y = -1