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Aleks [24]
3 years ago
14

A survey of 225 students showed the mean number of hours spent studying per week was 20.6 and the standard deviations was 2.7

Mathematics
2 answers:
Step2247 [10]3 years ago
6 0

Answer:

.3 is the answer.

Step-by-step explanation:

LekaFEV [45]3 years ago
5 0

Answer:

The margin of error is approximately 0.3

Step-by-step explanation:

The following information has been provided;

The sample size, n =225 students

The sample mean number of hours spent studying per week = 20.6

The standard deviation = 2.7

The question requires us to determine the margin of error that would be associated with a 90% confidence level. In constructing confidence intervals of the population mean, the margin of error is defined as;

The product of the associated z-score and the standard error of the sample mean. The standard error of the sample mean is calculated as;

\frac{sigma}{\sqrt{n} }

where sigma is the standard deviation and n the sample size. The z-score associated with a 90% confidence level, from the given table, is 1.645.

The margin of error is thus;

1.645*\frac{2.7}{\sqrt{225}}=0.2961

Therefore, the margin of error is approximately 0.3

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A paper cup is a perfect cylinder that is 6.4 cm tall and 3 cm across. Find the total area of paper needed to make the cup, to t
NNADVOKAT [17]

Hey there! I'm happy to help!

We want to find how much paper we need to make the cup. So, we need to find the surface area of the cylinder, which is basically the "walls and floors" of the cup. So, this is the circle on the bottom and the surrounding stuff that goes up. There is no circular top to this cup, which will be important when finding the total area of paper.

So, first we need to find how much paper we need to make the bottom circle. The formula for the area of a circle is A=πr². This r represents the radius, or the distance from the center of the circle to the edge. We are given that the cup is 3 cm completely across, and the radius is be half of that, so the radius is 1.5 cm. Let's find the area. We will use 3.14 for π.

π×1.5²=7.065

Now, we need  to find the area of the walls of the cup. The wall is a rectangle that is basically wrapped around the circle. The height of the rectangle is the height of the cup and the length of the rectangle is the circumference (perimeter) of the bottom circle because the length of the rectangle wraps completely around the circle.

First, let's find the circumference of the circle. The circumference is the diameter (distance across the circle, so 3 cm) multiplied by π. We will use 3.14 for π.

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Now, we add the rectangle area and the bottom circle area.

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But, they want us to round to the nearest centimetre, so we will just say 67 square centimetres.

An important thing to note is that this is not  the area of a normal cylinder (one with a top and a bottom circle) because it is a cup so it does not have a top. If you have a cylinder with a top and a bottom, you would just multiply the area of the circle by two, so then you have the top and bottom. If that were the case, the area of our cylinder would be 74 cm with the numbers we have been given here.

Have a wonderful day!

3 0
3 years ago
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svet-max [94.6K]

Answer:

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Step-by-step explanation:

z2 - 2z + 15

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0 + 15

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Goshia [24]

Answer:

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Step-by-step explanation:

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Hope it helps!

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