Can someone help me on this, I suck at math lol

jeff wants to buy a phone card for long distance calls. he can buy a 200-minute card for $10.00 or a 300-minute card for $12.00.

Alenkasestr [34]

200 min / $10.00 = 20 minutes / dollar

300 min / $12.00 = 25 minutes / dollar 

The cost of the 300 minute card is cheaper per minute and a better value. 

If you don't expect to use more than 200 minutes then save your money and buy the smaller card.

3 0

3 years ago

Read 2 more answers

HELPPPPPPPPP i have the most trouble with math what’s the answer??

lakkis [162]

Answer:

Second Option

$\frac{5\sqrt{11} +5\sqrt{3}}{8}$

Step-by-step explanation:

To simplify the expression you must multiply the numerator and the denominator of the fraction by the conjugate of the denominator.

If you have an expression of the form

$a -b$ then its conjugate will be $a + b.$

The result of that multiplication will be

$a ^ 2 -b ^ 2$

Therefore we have the expression

$\frac{5}{\sqrt{11} -\sqrt{3}}$

By multiplying by the conjugate of the denominator we have

$\frac{5}{\sqrt{11} -\sqrt{3}}*\frac{\sqrt{11} +\sqrt{3}}{\sqrt{11} +\sqrt{3}}\\\\\\\frac{5(\sqrt{11} +\sqrt{3})}{(\sqrt{11})^2 -(\sqrt{3})^2}\\\\\\\frac{5\sqrt{11} +5\sqrt{3}}{11 -3}\\\\\\\frac{5\sqrt{11} +5\sqrt{3}}{8}$

6 0

3 years ago

Please help with this one

anyanavicka [17]

Ok this inequality tells you the number of devices you can have before the new plan costs more than the old plan. The new plan expression is $4.50x + $94m = y ( total cost). The old plan is $175m = y (total cost). You can see m (number of months) in both equations, you don't need it this time since we're going to to compare both to one month. Since they're both equal to y you can make them equal to each other. $4.50x + $94 = $175. Now you want to figure when the new plan is less than the old plan you switch the equal sign for a less than sign. $4.50x + $94 < $175; this will help you find the inequality you want. From there just use algebraic steps to find that x has to less than 18 or

x < 18.

3 0

3 years ago

Mutually exclusive..

mrs_skeptik [129]

Answer:

there are no answer choices

Step-by-step explanation:

sorry can't help

8 0

3 years ago

Assume the average height for American women is 64 inches with a standard deviation of 2 inches. A sorority on campus wonders if

satela [25.4K]

Answer:

a) s = 0.4

b) Z = 2.5

c) 99th percentile.

d) The larger sample size would lead to a smaller margin of error, which would lead to a higher z-score and a increased percentile.

Step-by-step explanation:

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

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the z-score 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 p-value, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem establishes 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.

Assume the average height for American women is 64 inches with a standard deviation of 2 inches

This means that $\mu = 64, \sigma = 2$

A) Calculate the standard error for the distribution of means.

Sample of 25 means that $n = 25$ , so $s = \frac{2}{\sqrt{25}} = 0.4$ .

B) Calculate the z statistic for the sorority group.

Sample mean of 65 means that $X = 65$ .

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

By the Central Limit Theorem

$Z = \frac{X - \mu}{0.4}$

$Z = \frac{65 - 64}{0.4}$

$Z = 2.5$

C) What is the approximate percentile for this sample? Enter as a whole number.

Z = 2.5 has a p-value of 0.9938, so 0.99*100 = 99th percentile.

D) If the sorority actually had 36 members (still with an average of 65 inches), would you expect the percentile value to increase or decrease? why?

The larger sample size would lead to a smaller margin of error, which would lead to a higher z-score and a increased percentile.

3 0

3 years ago