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2 years ago

Anita needs to buy 7 1/2 feet of packaging tape. There are 1 1/2 feet of tape on each roll. How

Mathematics

1 answer:

valkas [14]2 years ago

8 0

Answer:

Step-by-step explanation:

you don't have to but i convert 7 1/2 and 1 1/2 into 7.5 and 1.5 to make it easier than you divide.

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What is the value of the expression 100 - 92 ÷ 3?

lora16 [44]

Answer:

2.67

Step-by-step explanation:

100-92=8

8÷3

$\sqrt[3]{8}$

=2.67

8 0

3 years ago

Read 2 more answers

g A psychic was tested for extrasensory perception (ESP). The psychic was presented with cards face down and asked to determine

diamong [38]

Answer:

Step-by-step explanation:

Hello!

The objective is to test ESP, for this, a psychic was presented with cards face down and asked to determine if each of the cards was one of four symbols: a star, cross, circle, square.

Be X: number of times the psychic identifies the symbols on the cards correctly is a size n sample.

p the probability that the psychic identified the symbol on the cards correctly

You have to calculate the sample size n to estimate the proportion with a confidence level of 95% and a margin of error of d=0.01

The CI for the population proportion is constructed "sample proportion" ± "margin of error" Symbolically:

p' ± $Z_{1-\alpha /2} * (\sqrt{\frac{p'(1-p')}{n} } )$

Where $d= Z_{1-\alpha /2} * (\sqrt{\frac{p'(1-p')}{n} } )$ is the margin of error. As you can see, the formula contains the sample proportion (it is normally symbolized p-hat, in this explanation I'll continue to symbolize it p'), you have to do the following consideration:

Every time the psychic has to identify a card he can make two choices:

"Success" he identifies the card correctly

"Failure" he does not identify the card correctly

If we assume that each symbol has the same probability of being chosen at random P(star)=P(cross)=P(circle)=P(square)= 1/4= 0.25

Let's say, for example, that the card has the star symbol.

The probability of identifying it correctly will be P(success)= P(star)= 1/4= 0.25

And the probability of not identifying it correctly will be P(failure)= P(cross) + P(circle) + P(square)= 1/4 + 1/4 + 1/4= 3/4= 0.75

So for this experiment, we'll assume the "worst case scenario" and use p'= 1/4 as the estimated probability of the psychic identifying the symbol on the card correctly.

The value of Z will be $Z_{1-\alpha /2}= Z_{0.975}= 1.96$

Now using the formula you have to clear the sample size:

$d= Z_{1-\alpha /2} * (\sqrt{\frac{p'(1-p')}{n} } )$

$\frac{d}{Z_{1-\alpha /2}} = \sqrt{\frac{p'(1-p')}{n} }$

$(\frac{d}{Z_{1-\alpha /2}})^2 =\frac{p'(1-p')}{n}$

$n*(\frac{d}{Z_{1-\alpha /2}})^2 = p'(1-p')$

$n = p'(1-p')*(\frac{Z_{1-\alpha /2}}{d})^2$

$n = (0.25*0.75)*(\frac{1.96}{0.01})^2= 7203$

To estimate p with a margin of error of 0.01 and a 95% confidence level you have to take a sample of 7203 cards.

I hope this helps!

5 0

3 years ago

Read 2 more answers

Which is a composite number<br> 81<br> 61<br> 71<br> 41

Ne4ueva [31]

Answer:

Step-by-step explanation:

A composite number has factor more than just one and itself.

Factors of 81=

1, 3, 9, 27, 81

4 0

3 years ago

Mica and Denise are reading the same novel. Mica has read 1/2 of the novel,Denise has read 1/3 of the novel . How much more of t

Diano4ka-milaya [45]

The answer would be 1/6 more.

5 0

3 years ago

Corinne has a job selling magazines. She earns $7.50 per hour plus 20% of the total amount of her sales. She also gets an allowa

maw [93]

PART A
Coefficient
Coefficient h is 7.50
Coefficient s is 0.20

Variable
h and s

Constant
40

PART B
7.50h + 0.20s + 40
= 7.50(25) + 0.20(300) + 40
= 187.5 + 60 + 40
= 287.5
She earns $287.5

PART C
Yes, the coefficient of h would change to 9, the rests are still the same. Because she's no longer receive 7.50 per hour, and start earning 9 per hour, so the coefficient should change.
The expression would be
9h + 0.20s + 40

4 0

2 years ago