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3 years ago

14 bugs are crawling on the steps. Some of the bugs are black, and 4 are

Mathematics

1 answer:

docker41 [41]3 years ago

8 0

Answer:

b = 14-4

Step-by-step explanation:

Let the number of black bugs be b

Let the number of green bugs be g

If 14 bugs are crawling on the step, then;

b + g = 14 ....1

If there are 4 green bugs, then g = 4

Substitute g = 4 into the equation

b + g = 14

b + 4 = 14

b = 14 - 4

Hence the sentence that can be required to find the number of black bugs is b = 14-4

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2x+2(1960/x)=200 please help for math hw

sp2606 [1]

Two solutions:

1. x =(100-√2160)/2=50-6√ 15 = 26.762

2. x =(100+√2160)/2=50+6√ 15 = 73.238

3 0

3 years ago

2(6 − 2x) + 3x = 4 + 2(5 + x) what is x

alexira [117]

First let's get rid of the parenthesis:

12 - 4x + 3x = 4 + 10 + 2x

Now group the x's on the left and the numbers on the right

-4x + 3x - 2x = 4 + 10 - 12

...and simplify

-3x = 2

divide by -3 to isolate x

x = -2/3

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 $z_{\alpha/2}=1.64$