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Dafna1 [17]
3 years ago
10

A professor has recorded exam grades for 10 students in his​ class, but one of the grades is no longer readable. If the mean sco

re on the exam was 80 and the mean of the 9 readable scores is 85​, what is the value of the unreadable​ score?
Mathematics
1 answer:
Nostrana [21]3 years ago
4 0

Answer:

unreadable score = 35

Step-by-step explanation:

We are trying to find the score of one exam that is no longer readable, let's give that score the name "x". we can also give the addition of the rest of 9 readable s scores the letter "R".

There are two things we know, and for which we are going to create equations containing the unknowns "x", and "R":

1) The mean score of ALL exams (including the unreadable one) is 80

so the equation to represent this statement is:

mean of ALL exams = 80

By writing the mean of ALL scores (as the total of all scores added including "x") we can re-write the equation as:

\frac{R+x}{10} =80

since the mean is the addition of all values divided the total number of exams.

in a similar way we can write what the mean of just the readable exams is:

\frac{R}{9} = 85\\ (notice that this time we don't include the grade x in the addition, and we divide by 9 instead of 10 because only 9 exams are being considered for this mean.

Based on the equation above, we can find what "R" is by multiplying both sides by 9:

\frac{R}{9} = 85\\R=85*9= 765

Therefore we can now use this value of R in the very first equation we created, and solve for "x":

\frac{R+x}{10} =80\\\frac{765+x}{10} =80\\765+x=80*10=800\\765+x=800\\x=800-765=35

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6 0
3 years ago
3. Which of the following is a polynomial with roots 4,6, and - 7
Vladimir79 [104]

Answer: P(x)=  x³ - 3 x² - 46 x +168

Step-by-step explanation:

(4,6, -7)

hence the polynomial will be equal to

P(x) = (x-4) (x-6) (x+7)

P(x) = (x-4) (x²+7 x -6 x -42)

P(x) = (x-4) (x²+x -42)

P(x) = x³ + x²-42 x -4 x² -4 x +168

P(x) =  x³ - 3 x² - 46 x +168

hence, the required polynomial is P(x) =  x³ - 3 x² - 46 x +168

<h2>Have a awesome day✨</h2>

5 0
3 years ago
Emerson purchased a game that was on sale for 18% off. The sales tax in his county is 8%. Let y represent the original price of
kolezko [41]

Answer:

(y-18%) + (y+8%)

Step-by-step explanation:

3 0
2 years ago
Please help and please tell me how you got the answer will mark brainliest
valentinak56 [21]

Answer:

Steve's pay is the highest and is equal to 55 dollars per hour.

The column for pay corresponding to 1 hour is $55.

Step-by-step explanation:

Geeta's pay:

The equation for Geeta's pay is given as:

p=75+45h

Where, 'p' is in dollars and 'h' is in hours.

The above equation is a linear equation of the form y=mx+b, where 'm' is the rate of change of pay or the pay per hour.

So, the pay per hour of Geeta is 45 dollars.

Richard's pay:

The graph of Richard's pay is a straight line. The slope of the line gives the rate of change of pay or the pay per hour.

The slope of the line is given as:

Slope = Rise over run = \frac{80-50}{1-0}=30 dollars per hour.

So, Richard's pay per hour is 30 dollars.

Steve's pay:

The table of hours and pay is given.

The rate of change or pay per hour can be obtained by using two values of both hours and pay.

Consider h=3\ and\ h=5 and p=165\ and\ p=275

Now, pay per hour = \frac{275-165}{5-3}=\frac{110}{2}=55 dollars

Therefore, Steve's pay per hour is 55 dollars.

The column for pay corresponding to 1 hour is $55.

On comparing, Steve's pay is the highest and is equal to 55 dollars per hour.

6 0
3 years ago
The graph for y≥-3.<br>true<br>false<br>helpp me​
erica [24]
The answer is false.
5 0
3 years ago
Read 2 more answers
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