Polly bought a cracker for $3 and then bought a parrot for $4. By how much did Polly's account change after her transactions?

Mathematics

1 answer:

nikitadnepr [17]3 years ago

8 0

Answer: -7$ or down by 7$

Step-by-step explanation: Her account went down by 7 or x - 7.

Hope this helped!

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A black-tailed jackrabbit hops about 7 feet in a single hop how far can a hop in 5 seconds

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The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customer

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Answer:

$4-2.326\frac{1}{\sqrt{100}}=3.767$

$4+2.326\frac{1}{\sqrt{100}}=4.233$

So on this case the 98% confidence interval would be given by (3.767;4.233)

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

$\bar X=4$ represent the sample mean

$\mu$ population mean (variable of interest)

$\sigma=1$ represent the population standard deviation

n=100 represent the sample size

Solution to the problem

The confidence interval for the mean is given by the following formula:

$\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (1)

Since the Confidence is 0.98 or 98%, the value of $\alpha=0.02$ and $\alpha/2 =0.01$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.01,0,1)".And we see that $z_{\alpha/2}=2.326$

Now we have everything in order to replace into formula (1):

$4-2.326\frac{1}{\sqrt{100}}=3.767$

$4+2.326\frac{1}{\sqrt{100}}=4.233$

So on this case the 98% confidence interval would be given by (3.767;4.233)

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3 years ago

Jack recieved $600 for his birthday. If he saves it in a bank account with 8% interest compounded yearly, how much money will he

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so 21 - 13, the money will be invested for 8 years.

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