Can someone please help

Mathematics

1 answer:

Anastasy [175]3 years ago

6 0

Point slope form is

y - y1 = m(x - x1) where m = slope and (x1, y1) is a point on the line.

Plugging in the given values:-

y - 1.4 = 1.8(x - (-4.5))

y - 1.4 = 1.8(x + 4.5) So the correct choice is A.

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Wholesale cost of a telescope: $199.50; Markup: 50%, Discount: 30%,

kupik [55]

Answer:

$2147.85

Step-by-step explanation:

199.5*.5=99.75

199.5+99.75=299.25

299.25*.3=89.775

299.25-89.775=209.475

209.475*.04=8.279

209.475+8.379=217.854

7 0

3 years ago

In an examination of purchasing patterns of shoppers, a sample of 16 shoppers revealed that they spent, on average, $54 per hour

Lesechka [4]

Answer:

$54-1.64\frac{21}{\sqrt{16}}=45.39$

$54 +1.64\frac{21}{\sqrt{16}}=62.61$

So on this case the 90% confidence interval would be given by (45.39;62.61)

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".

$\bar X=54$ represent the sample mean

$\mu$ population mean (variable of interest)

$\sigma=21$ represent the sample standard deviation

n=16 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 0.90 or 90%, the value of $\alpha=1-0.9=0.1$ and $\alpha/2 =0.05$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.05,0,1)".And we see that $z_{\alpha/2}=1.64$