Question

A set of N = 20 exam scores has a mean of m = 50. The instructor discovered that an error was made grading one exam, so 20 points are added to that student's score. After adding the 20 points, what is the new mean for the class? Hint: Write down the formula for the mean and fill in all known information. What is the new mean for the class?

Answer 1

Answer:

The new mean for the exam scores is 51

Step-by-step explanation:

the mean can be calculated using the formula

mean of scores = $\frac{Sum total of scores}{Number of students}$

before the 20 points was added, the mean of the score was = 50.

Inserting this into the formula, we have:

50 = $\frac{Sum total}{20 students}$

from this, we can compute the sum total of the scores as

sum total = 50 × 20 = 1000

when the extra 20 marks is added, the sum of the entire scores will be changed to 1000 + 20 = 1020.

Hence the new mean will be computed as (New Sum total of scores / Number of students)

= $\frac{1020}{20}$ = 51.

∴ The new mean of the scores is = 51

Answer 2

"51" would be the new mean of the scores.

Given:

Set,

• N = 2

Mean,

• m = 50 (before 20 points was added)

The total sum of the score will be:

= $50\times 20$

= $1000$

When 20 marks added to the total, the

= $1000+20$

= $1020$

hence,

The new mean will be:

= $\frac{New \ total \ sum \ of \ scores}{Number \ of \ students}$

= $\frac{1020}{20}$

= $51$

Thus the above answer is right.

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