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zavuch27 [327]
2 years ago
15

A science teacher gives a test with 15 questions. This teacher is a hard grader. The teacher assigns points in the following man

ner: a correct answer =+1 point, an incorrect answer =−1 point, no answer =0 points. So scores on the test could range from +15 to −15. The teacher’s assistant calculates the standard deviation for scores on the test and reports SD =−2.3. What do we know?
- The standard deviation was calculated incorrectly.
- Most students received negative scores.
- Most students scored below the mean.
- There is an outlier that has a negative value close to -15.
Mathematics
1 answer:
ASHA 777 [7]2 years ago
6 0

Answer:  The standard deviation was calculated incorrectly.

Step-by-step explanation:

  • The standard deviation measures the dispersion of the data values from the mean value.

It cannot be negative , because it is the square root of the variance .

We add all squared deviations from the data points away from the mean and (then divide it by the number of data values) to evaluate variance.

Since , any squared number cannot give a negative result.

⇒ Standard deviation cannot be negative.

⇒The standard deviation was calculated incorrectly.

Rest other things (given in options) can not be interpreted on the basis of given information.

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Find the sum of the arithmetic sequence 22, 11, 0, -11, ..., –77.
blagie [28]

Answer:

B.

Step-by-step explanation:

First you need to figure out how many numbers there are, so with this you can simply count 10. Then use the formula to plug in the numbers: 10(22-77)/2 to get the answer.

7 0
3 years ago
3 3/4+ (-4 1/3)<br> Simplify
IgorC [24]

Answer:

-7/12 in decimal form it would be -0.583

Step-by-step explanation:

convert the mixed number to an improper fraction

(when there's a + in front of an expression in parentheses the expression remains the same)

15/4+(-4 1/3)

convert the mixed number to an improper fraction

15/4-13/3

subtract the fractions to get -7/12

4 0
3 years ago
QUESTION 8 Write an inequality to represent the real-world problem. Then explain how you created the inequality. You have caviti
Marizza181 [45]

Answer:

I can give you alittle head start. I hope it kinda helps.

Step-by-step explanation:

Dentist A: 50 + 20x

Dentist B: 70 + 5x

It cost 20 more dollars for the visit and 15 dollars less for each cavaty at Dentist B.

6 0
3 years ago
I need help with this problem. <br>​
Zina [86]

Answer:

(1,4)

Step-by-step explanation:

Let's this of y=\sqrt{x} which is it's parent function.

How do we get to y=-\sqrt{x-1}+4 from there?

It has been reflected about the a-axis because of the - in front of the square root.

It has been shifted right 1 unit because of the -(1) in the square root.

It has been moved up 4 units because of the +4 outside the square root.

In general:

y=a(x-h)^2+k has the following transformations from the parent:

Moved right h units if h is positive.

Moved left h units if h is negative.

Moved up k units if k is positive.

Moved down k units if k is negative.

If a is positive, it has not been reflected.

If a is negative, it has been reflected about the x-axis.

a also tells us about the stretching factor.

The parent function has a starting point at (0,0).  Where does this point move on the new graph?

It new graphed was the parent function but reflected over x-axis and shifted right 1 unit and moved up 4 units.

So the new starting point is (0+1,0+4)=(1,4).

6 0
2 years ago
Read 2 more answers
Chris bought "c" tickets to a movie for $9 each. Michael bought " m" tickets to another movie for $10 each. Write an expression
Fynjy0 [20]

<u>Answer:</u>

9c + 10 (see below)

<u>Step-by-step explanation:</u>

To find how much Chris spent on tickets, you can write an expression to represent the situation:

$9c

You can do this to find how much Michael spent as well:

$10m

To find how much Chris and Michael spent combined, add their two costs:

9c + 10

5 0
3 years ago
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