Matthew threw 55 pitches in a baseball game. Of those pitches, 4/5 were strikes.

If x and y are real numbers such that x > 0 and y < 0, then

klemol [59]

Answer:

Step-by-step explanation:

The third one

8 0

2 years ago

The product of the ages of all teenagers at Joyce’s birthday party last Saturday was 2971987200. The number of 18 year olds who

Elenna [48]

Click here to see ALL problems on Age Word Problems

Question 1128242: The product of the three ages, in years of three teenagers is 4590. None of the teens are the same ages. What are the ages of the three teen ages? (Use guess and check)

A hat and a jacket cost $100. The jacket cost $90 more than the hat. What are the cost of the hat and the cost of the jacket?

Melody picks a number. She doubles the number, squares are result, divide the square by 3 subtracts 30 from the quotient and gets 18. What are the possible numbers that Melody could have picked? What operation does Melody perform that prevents us from knowing 100% certainly which she picked?

(Scroll Down for Answer!)

Did you know that Algebra.Com has hundreds of free volunteer tutors who help people with math homework? Anyone can ask a math question, and most questions get answers!

OR get immediate PAID help on:

Type Your Question

Go!!!

Answer by greenestamps(9721) About Me (Show Source):

You can put this solution on YOUR website!

These are three very different problems. The rules of the forum are one problem per post. Please follow those rules in the future.

(1) Certainly guess and check is the easiest way to solve this problem, since you know the three ages are whole numbers. But you should be able to get to the solution with very few if any wrong "guesses" by making your guesses logically.

The product of the three ages is a multiple of 10, and therefore a multiple of 5; since all three ages are in the teens, one of them has to be 15. Then 4590/15 = 306.

You could do guess and check again from there. However, if you note that both the other ages have to be greater than 15, and you know the last digit of the product has to be "6", then the only possible pair of ages is 17 and 18. And indeed 17*18 is 306.

ANSWER: The ages are 15, 17, and 18.

(2) Here is an informal solution method using logical reasoning.

Take away the "extra" $90 that the jacket costs; you are left with a jacket and a hat that each cost the same, and the total is now $100-$90 = $10. That means each of them costs $5. Now add those extra $90 back on to the price of the jacket.

ANSWER: The jacket costs $95; the hat costs $5.

(3) Melody picks a number: Call it x.

She doubles the number: It is now 2x.

She squares are result: It is now (2x)^2 = 4x^2.

She divides the square by 3: It is now 4x^2/3.

She subtracts 30 from the quotient: It is now 4x^2/3-30.

The number she ends up with is 18.

Solve the equation that says 4x^2/3-30 = 18:

4x%5E2%2F3-30+=+18

4x%5E2%2F3+=+48

4x%5E2+=+144

x%5E2+=+36

x+=+6 or x+=+-6

ANSWER: The two possible starting numbers are 6 and -6. We get two possible answers because of the step where she squares the number.

6 0

3 years ago

Read 2 more answers

A manufacturer cuts squares from the corners of a rectangular plece of sheet metal that measures 2 inches by 7 inches (see Figur

Vladimir79 [104]

Answer:

The value of x that maximizes the volume enclosed by this box is 0.46 inches

The maximum volume is 3.02 cubic inches

Step-by-step explanation:

see the attached figure to better understand the problem

we know that

The volume of the open-topped box is equal to

$V=LWH$

where

$L=(7-2x)\ in\\W=(2-2x)\ in\\H=x\ in$

substitute

$V=(7-2x)(2-2x)x$

Convert to expanded form

$V=(7-2x)(2-2x)x\\V=(14-14x-4x+4x^{2})x\\V=14x-14x^2-4x^2+4x^{3}\\V=4x^{3}-18x^{2} +14x$

using a graphing tool

Graph the cubic equation

Remember that

The domain for x is the interval -----> (0,1)

Because

If x>1

then

the width is negative (W=2-2x)

so

The maximum is the point (0.46,3.02)

see the attached figure

therefore

The value of x that maximizes the volume enclosed by this box is 0.46 inches

The maximum volume is 3.02 cubic inches

8 0

3 years ago

Life Expectancies In a study of the life expectancy of people in a certain geographic region, the mean age at death was years an

Sphinxa [80]

Answer:

The probability that the mean life expectancy of the sample is less than X years is the p-value of $Z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}$ , in which $\mu$ is the mean life expectancy, $\sigma$ is the standard deviation and n is the size of the sample.

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.

We have:

Mean $\mu$ , standard deviation $\sigma$ .

Sample of size n:

This means that the z-score is now, by the Central Limit Theorem:

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

Find the probability that the mean life expectancy will be less than years.

The probability that the mean life expectancy of the sample is less than X years is the p-value of $Z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}$ , in which $\mu$ is the mean life expectancy, $\sigma$ is the standard deviation and n is the size of the sample.

8 0

2 years ago

Bobby’s uncle gave him 300 baseball cards. Each week, Bobby purchases 40 baseball cards to add to his collection.

Julli [10]

Answer:

C

Step-by-step explanation:

4 0

3 years ago

Read 2 more answers