Please need help on this!

A population has a mean of 200 and a standard deviation of 50. Suppose a sample of size 100 is selected and x is used to estimat

zmey [24]

Answer:

a) 0.6426 = 64.26% probability that the sample mean will be within +/- 5 of the population mean.

b) 0.9544 = 95.44% probability that the sample mean will be within +/- 10 of the population mean.

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal probability distribution

When the distribution is normal, we use the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$ .

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

In this question, we have that:

$\mu = 200, \sigma = 50, n = 100, s = \frac{50}{\sqrt{100}} = 5$

a. What is the probability that the sample mean will be within +/- 5 of the population mean (to 4 decimals)?

This is the pvalue of Z when X = 200 + 5 = 205 subtracted by the pvalue of Z when X = 200 - 5 = 195.

Due to the Central Limit Theorem, Z is:

$Z = \frac{X - \mu}{s}$

X = 205

$Z = \frac{X - \mu}{s}$

$Z = \frac{205 - 200}{5}$

$Z = 1$

$Z = 1$ has a pvalue of 0.8413.

X = 195

$Z = \frac{X - \mu}{s}$

$Z = \frac{195 - 200}{5}$

$Z = -1$

$Z = -1$ has a pvalue of 0.1587.

0.8413 - 0.1587 = 0.6426

0.6426 = 64.26% probability that the sample mean will be within +/- 5 of the population mean.

b. What is the probability that the sample mean will be within +/- 10 of the population mean (to 4 decimals)?

This is the pvalue of Z when X = 210 subtracted by the pvalue of Z when X = 190.

X = 210

$Z = \frac{X - \mu}{s}$

$Z = \frac{210 - 200}{5}$

$Z = 2$

$Z = 2$ has a pvalue of 0.9772.

X = 195

$Z = \frac{X - \mu}{s}$

$Z = \frac{190 - 200}{5}$

$Z = -2$

$Z = -2$ has a pvalue of 0.0228.

0.9772 - 0.0228 = 0.9544

0.9544 = 95.44% probability that the sample mean will be within +/- 10 of the population mean.

7 0

3 years ago

100m world record was completed at an average speed of 37.6 km/h. work out this speed in meters per second?

pickupchik [31]

Step-by-step explanation:

1 km = 1000 m

1 hour = 3600 s

so,

37.6 km = 37,600 m (still per hour or per 3600 s).

in 1 second now that is

37600/3600 = 10.44444444... m/s

4 0

2 years ago

Abc bookstore sells new books, n, for $12, used books, u, for $8, and magazines, m, for $5 each. The store earned $340 revenue l

poizon [28]

Answer:

The number of new books sold = 10

The number of used books sold (u) = 15

The number of magazines sold (m) = 20

Step-by-step explanation:

Let us assume the number of new books = n

So, the number of used books sold (u) = New books sold + 5 = n + 5

Also, the number of magazines sold (m) = 2 x ( Number of new books sold)

= 2 n

⇒ u = n + 5, m = 2 n

Here, the cost of each new book n- = $12

So, the cost of n new books = n x ($12) = 12 n

the cost of each used book u = $8

So, the cost of u = (n+ 5) used books = n+5 x ($8) = 8 n + 40

the cost of each magazine m = $5

So, the cost of m = (2n ) magazines = 2n x ($5) = 10 n

Also, total earnings = $340

⇒ 12 n + 8n +40 + 10 n = 340

or, 30 n = 300

or,n = 300/30 = 10

Hence the number of new books sold = n = 10

The number of used books sold (u) = n + 5 = 15

The number of magazines sold = m = 2 n = 20

4 0

3 years ago

163.64 nearest cent?????????????????????????

Afina-wow [57]

163.65 since it would meet in the middle

3 0

3 years ago

Read 2 more answers

Which of the following fractions compares BC to BD?

Hoochie [10]

Answer:

(2/4)/(4/4) = 0.5 or 2/4

Step-by-step explanation:

7 0

2 years ago