help please I need these finished by today!

In a random sample of 18 families, the average weekly food expense was $95.60 with a sample standard deviation of $22.50. Determ

shepuryov [24]

Answer:

t-distribution should be used to construct a confidence interval.

Step-by-step explanation:

We are given that a random sample of 18 families, the average weekly food expense was $95.60 with a sample standard deviation of $22.50.

We have to determine whether a normal distribution (Z values) or a t- distribution should be used or whether neither of these can be used to construct a confidence interval.

<em><u>Since in this question we are provided with;</u></em>

Sample average weekly food expense, $\bar X$ = $95.60

Sample standard deviation, s = $22.50

Sample of families, n = 18

The distribution that we will use here to construct a confidence interval will be <u>t-distribution</u> because in the question we don't know anything about population standard deviation $(\sigma)$ .

Normal distribution is used when we know population standard deviation $(\sigma)$ .

So, the pivotal quantity for confidence interval that will be used is One-sample t-test statistics;

P.Q. = $\frac{\bar X -\mu}{\frac{s}{\sqrt{n} } }$ ~ $t_n_-_1$

Therefore, t-distribution should be used to construct a confidence interval.

3 0

3 years ago

Lee ran a mile in 7 1/3 minutes. His friend Sam ran the same mile in 8 5/9 minutes. How many minutes faster did Lee run? (First

Anna [14]

Answer:

1 2/9 minutes faster

Step-by-step explanation:

Take the larger number and subtract the smaller number

8 5/9 minutes - 7 1/3 minutes

Get a common denominator

8 5/9 - 7 1/3 *3/3

8 5/9 - 7 3/9

1 2/9 minutes faster

5 0

3 years ago

Two integers, a and b, have a product of 36. What is the least possible sum of a and b?

Minchanka [31]

<h3>Answer: 12</h3>

==============================================================

Explanation:

The two integers multiply to 36, so,

ab = 36

which solves to

a = 36/b

Then we want to add the numbers such that we get the smallest possible result.

a+b = (36/b)+b

So we want (36/b)+b to be as small as possible.

Let's say we replace b with x and we consider this function

f(x) = (36/x) + x

The goal is to find when f(x) is smallest, ie, we want to minimize the function.

If we were to graph out the function, we get the curve shown below.

To make things easier, we'll only focus on positive values of x.

The lowest part of the curve is what we're after. Using the "minimum" function/feature on the graphing calculator, we would then find the lowest point occurs at (6,12). This point is considered a local minimum because it's the lowest point in that given neighborhood of x values.

So the input x = 6 leads to the smallest output f(x) = 12.

This in turn means b = 6 is going to pair with a = 36/b = 36/6 = 6.

In short, a = 6 and b = 6.

----------------------

As a check,

a*b = 6*6 = 36

a+b = 6+6 = 12

We can make a table of various values to help confirm that 12 is the smallest sum.

Side note: If you're not allowed to use a graphing calculator, then you'll need to use calculus.

8 0

3 years ago

(69 points!) Some1 please solve. (69 points!)

MAVERICK [17]

Answer:

for the second questio it is certainly The last choice D

Step-by-step explanation:

5 0

3 years ago

Find all the zeroes of the equation and show your work<br> -3x^4 + 27x^2 + 1200 = 0

s344n2d4d5 [400]

Answer:i try checking the internet

Step-by-step explanation:

fgnjjjjjjjjcbkm/gijw'

eofsdkm;grfbkm

6 0

3 years ago

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￼help please I need these finished by today!

help please I need these finished by today!