I really need someone to answer this please, I really need to pass this test:(.

You are trying to estimate the average amount a family spends on food during a year. In the past the standard deviation of the a

svetoff [14.1K]

Answer:

$n=(\frac{2.58(1000)}{50})^2 =2662.56 \approx 2663$

So the answer for this case would be n=2663 rounded up to the nearest integer

Step-by-step explanation:

We have the following info:

$ME = 50$ margin of error desired

$\sigma = 1000$ the standard deviation for this case

The margin of error is given by this formula:

$ME=z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (a)

And on this case we have that ME =50 and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=(\frac{z_{\alpha/2} \sigma}{ME})^2$ (b)

The critical value for 99% of confidence interval now can be founded using the normal distribution. The significance is $\alpha=0.01$ . And for this case would be $z_{\alpha/2}=2.58$ , replacing into formula (b) we got:

$n=(\frac{2.58(1000)}{50})^2 =2662.56 \approx 2663$

So the answer for this case would be n=2663 rounded up to the nearest integer

5 0

2 years ago

Barbara made a bad investment. Rather than earning interest, her money is decreasing in value by 11% each week! After just one w

pochemuha

Answer: She started with $160.

It will take 6 weeks before she has less than half of what she originally invested.

Step-by-step explanation:

If her money is decreasing in value by 11% each week, it means that the rate at which it is decreasing is exponential.

We would apply the formula for exponential decay which is expressed as

A = P(1 - r)^t

Where

A represents the value of the investment after t weeks.

t represents the number of weeks.

P represents the initial value of the investment.

r represents rate of depreciation.

From the information given,

A = $142.40

r = 11% = 11/100 = 0.11

t = 1

Therefore

142.40 = P(1 - 0.11)^1

142.40 = P(0.89)

P = 142.4/0.89

P = 160

For her to have half of what she invested originally, then

80 = 160(0.89)^t

80/160 = (0.89)^t

0.5 = (0.89)^t

Taking log of both sides to base 10

Log 0.5 = log0.89^t = tlog0.89

- 0.3010 = - 0.051t

t = - 0.3010/- 0.051

t = 5.9

Approximately 6 weeks

5 0

3 years ago

Need help, Write the equation of the line that passes through the points (-2, -3) and (8,3) first in point-slope form, and then

Allushta [10]

Answer:

the slope intercept formula would be: y=3/4x-3. Hope this helps!

Step-by-step explanation:

3 0

2 years ago

Alaina has $28 in her account. She wants to purchase a pair of shoes that costs $45. If Alaina makes the purchase, which integer

k0ka [10]

Alaina has $28 in her account and wants to buy shoes worth $45

So $28-$45=$-17

Her account status will be $ - 17

Hope this helps

3 0

3 years ago

Read 2 more answers

Joe Summers buys a gas grill and accessories. The cost, including tax, amounts to $850.00. Joe finances the grill over 12 months

Anettt [7]

Answer:

$66.5

Step-by-step explanation:

The cost, including tax, amounts to $850.00.

Down payment =$150

Amount after paying down payment = $850-$150=$700

Interest rate = 14 %

So, interest on $700 = $\frac{14}{100} \times 700 =98$

So, c = $98

Total payment = amount financed + c = 700+98=$798

Now Joe finances the grill over 12 months

So, no. of payments = 12

Now Monthly payment = Total of payments ÷ number of payments

=798 ÷ 12

=$66.5

Hence Joe's monthly payments (principal plus interest) is $ 66.5

7 0

2 years ago