Ascience teacher gives a test with 15 questions. this teacher is a hard grader. the teacher assigns points in the following manner: 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.

 The standard deviation was calculated incorrectly.

Step-by-step explanation:

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.

3

step-by-step explanation:

in standard form:

a= dictionaries

b= maps

you have to buy 3 dictionaries, so put a 3 next to the a (dictionaries) so that you can multiply them by each other.

a3+b= 60 (the amount of money you have)

we already know the cost of a=15 so replace a with $15

($15 x 3)+b=60

multiply 15 and 3 to get $45 and replace it with $45

45+b=60

and then replace b with 15 to get the total:

45+15=60

that means you have $15 left after buying 3 dictionaries.

15 divided by the cost of a map ($5) equals 3.

so you can buy 3 maps.

sorry if it was confusing!

greater than one

step-by-step explanation: