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Mashutka [201]
3 years ago
15

A college is selling tickets for a winter fund-raiser. One day, Krissa sold 14 adult tickets and 8 student tickets for a total o

f $376. The next day, she sold 7 adult tickets and 11 student tickets for a total of $272. Krissa wanted to find the price of one adult ticket, a, and the price of one student ticket, s. She wrote and solved the following system of equations.
14a+8s=376
7a+11s=272

She found that the price of one student ticket is $20 and the price of one adult ticket is $12. Which statement explains Krissa’s error?

A She switched the prices of the tickets.
B The solution works in both equations.
C The solution only gives the correct price for one student ticket.
Mathematics
2 answers:
FinnZ [79.3K]3 years ago
6 0

Answer: She switched the prices of the tickets.

Explanation Oof Oof Oof Oof

FromTheMoon [43]3 years ago
5 0

The statement which explains Krissa’s error is "She switched the prices of the tickets" ⇒ A

Step-by-step explanation:

A college is selling tickets for a winter fund-raiser

  • One day, Krissa sold 14 adult tickets and 8 student tickets for a total of $376
  • The next day, she sold 7 adult tickets and 11 student tickets for a total of $272
  • The price of one adult ticket is a
  • The price of one student ticket is s
  • She wrote and solved the following system of equations.  14a + 8s = 376  and 7a + 11s = 272
  • She found that the price of one student ticket is $20 and the price of one adult ticket is $12

We need to find which statement explains Krissa’s error

∵ The system of equations is:

   14a + 8s = 376  ⇒ (1)

    7a + 11s = 272 ⇒ (2)

Multiply equation (2) by -2 to eliminate x

∵ -14a - 22s = -544 ⇒ (3)

Add equations (1) and (3)

∴ -14s = -168

Divide both sides by -14

∴ s = 12

Substitute the value of s in equation (2) to find a

∵ 7a + 11(12) = 272

∴ 7a + 132 = 272

Subtract 132 from both sides

∴ 7a = 140

Divide both sides by 7

∴ a = 20

∵ a represents the price of one adult ticket

∴ The price of one adult ticket is $20

∵ s represents the price of one student ticket

∴ The price of one student ticket is $12

∵ She found that the price of one student ticket is $20 and

   the price of one adult ticket is $12

- She switched the prices of the tickets

∴ Her error is, she switched the prices of the tickets

The statement which explains Krissa’s error is "She switched the prices of the tickets"

Learn more:

You can learn more about the system of equations in brainly.com/question/2115716

#LearnwithBrainly

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Please help me solve this please
Tems11 [23]

Answer:

x = 8

Step-by-step explanation:

The sum of two interior angles in a triangle is equal to the exterior angle that's supplementary to the third interior angle:

7x + 6 + 22 = 9x + 12 add like terms

7x + 28 = 9x + 12 export like terms to the same side of the equation

28 - 12 = 9x - 7x

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6 0
3 years ago
Jill’s bowling scores are approximately normally distributed with mean 170 and standard deviation 20, while Jack’s scores are ap
miss Akunina [59]

Answer:

a) The probability of Jack scoring higher is 0.3446

b) They probability of them scoring above 350 is 0.2119

Step-by-step explanation:

Lets call X the random variable that determines Jill's bowling score and Y the random variable that determines jack's. We have

X \simeq N(170,400)\\Y \simeq N(160,225)

Note that we are considering the variance on the second entry, the square of the standard deviation.

If we have two independent Normal distributed random variables, then their sum is also normally distributed. If fact, we have this formulas:

N(\lambda_1, \sigma^2_1) + N(\lambda_2, \sigma^2_2) = N(\lambda_1 + \lambda_2,\sigma^2_1 + \sigma^2_2) \\r* N(\lambda_1, \sigma^2_1) = N(r\lambda_1,r^2\sigma^2_1)  

for independent distributions N(\lambda_1, \sigma^2_1) , N(\lambda_2, \sigma^2_2) , and a real number r.

a) We define Z to be Y-X. We want to know the probability of Z being greater than 0. We have

Z = Y-X = N(160,225) - N(170,400) = N(160,225) + (N(-170,(-1)^2 * 400) = N(-10,625)

So Z is a normal random variable with mean equal to -10 and vriance equal to 625. The standard deviation of Z is √625 = 25.

Lets work with the standarization of Z, which we will call W. W = (Z-\mu)/\sigma = (Z+10)/25. W has Normal distribution with mean 0 and standard deviation 1. We have

P(Z > 0) = P( (Z+10)/25 > (0+10)/25) = P(W > 0.4)

To calculate that, we will use the <em>known </em>values of the cummulative distribution function Φ of the standard normal distribution. For a real number k, P(W < k) = Φ(k). You can find those values in the Pdf I appended below.

Since Φ is a cummulative distribution function, we have P(W > 0.4) = 1- Φ(0.4)

That value of Φ(0.4) can be obtained by looking at the table, it is 0.6554. Therefore P(W > 0.4) = 1-0.6554 = 0.3446

As a result, The probability of Jack's score being higher is 0.3446. As you may expect, since Jack is expected to score less that Jill, the probability of him scoring higher is lesser than 0.5.

b) Now we define Z to be X+Y Since X and Y are independent Normal variables with mean 160 and 170 respectively, then Z has mean 330. And the variance of Z is equal to the sum of the variances of X and Y, that is, 625. Hence Z is Normally distributed with mean 330 and standard deviation rqual to 25 (the square root of 625).

We want to know the probability of Z being greater that 350, for that we standarized Z. We call W the standarization. W is s standard normal distributed random variable, and it is obtained from Z by removing its mean 330 and dividing by its standard deviation 25.

P(Z > 350) = P((Z  - 330)/25 > (350-330)/25) = P(W > 0.8) = 1-Φ(0.8)

The last equality comes from the fact that Φ is a cummulative distribution function. The value of Φ(0.8) by looking at the table is 0.7881, therefore P(X+Y > 350) = 1 - Φ(0.8) = 0.2119.

As you may expect, this probability is pretty low because the mean value of the sum of their combined scores is quite below 350.

I hope this works for you!

Download pdf
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3 years ago
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cluponka [151]

Answer:

Step-by-step explanation:

33×10^-3 is equivalent to 33/1000, or 0.033.

This, in turn, is equivalent to 3.3×10^(-2) (which is in scientific notation)

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Another teacher decides to average the height of all 15-year-old male students in his classes throughout the day. By the end of
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Answer: 0.47

Step-by-step explanation:

0.47% = 0.0047 in decimal form. Percent means 'per 57'. So, 67Inches means 0.47 per 100 or simply 0.47/100. If you divide 0.47 by 100, you'll get 0.0047 (a decimal number).

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