4. Mariana receives a $20 gift card for

Mathematics

1 answer:

Alenkasestr [34]3 years ago

6 0

Answer:

inequality- 1.29m <20

maximum number of songs- 15 songs

Step-by-step explanation:

For the inequality, you see that she only has $20 so whatever she buys has to be below that so use the less than sign. You also see that each song is worth $1.29 so 1.29m. For the maximum number of songs, you divide 20 by 1.29 and just ignore the remainder.

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Perform the indicated operation.(3/a+2) + (4/a-5)

kipiarov [429]

Answer:

$\frac{7(a-1)}{(a+2)(a-5)}$

Step-by-step explanation:

To solve this operation we need to find the common multiple of both denominators and solve for a.

$\frac{3}{a+2} + \frac{4}{a-5} =\frac{3(a-5)+4(a+2)}{(a+2)(a-5)} =\frac{3a-15+4a+8}{(a+2)(a-5)} =\frac{7a-7}{(a+2)(a-5)} =\frac{7(a-1)}{(a+2)(a-5)}$

Thus, the solution is 7(a -1) / (a+2)(a-5)

8 0

3 years ago

Graph the following piecewise function:

zhenek [66]

Check the picture below.

notice the solid circle at -4 and 3, since it includes those points.

also notice the dashed line, though the lines keeps on going those ways, is not included in the piece-wise, since it's not part fo the domain or constraints.

5 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 $z_{\alpha/2}=1.64$