On a certain exam, Tony corrected 10 papers and found

the mean for his group to be 70. Alice corrected the remaining
20 papers and found that the mean for her
group was 80. What is the mean of the combined group
of 30 students?

10 * 70 = 700

20 * 80 = 1600

700 + 1600 = 2300
2300 / 30 = ?

76.6

To find the mean of the combined group of 30 students, we need to calculate the total sum of all the scores and divide it by the total number of students.

Let's calculate the total sum of the scores:

For Tony's group:
Mean = Sum of scores / Number of students
70 = Sum of scores / 10
Sum of scores = 70 * 10 = 700

For Alice's group:
Mean = Sum of scores / Number of students
80 = Sum of scores / 20
Sum of scores = 80 * 20 = 1600

Now, let's calculate the total sum of all the scores:

Total sum of scores = Sum of scores for Tony's group + Sum of scores for Alice's group
Total sum of scores = 700 + 1600 = 2300

Finally, to find the mean of the combined group:
Mean = Total sum of scores / Total number of students
Mean = 2300 / 30 = 76.67 (rounded to two decimal places)

Therefore, the mean of the combined group of 30 students is 76.67.

To find the mean of the combined group, we need to determine the total sum of all the scores and then divide it by the total number of students.

First, let's find the sum of all the scores.

For Tony's group:
Tony corrected 10 papers and found the mean to be 70. This means the sum of the scores for his group is 10 x 70 = 700.

For Alice's group:
Alice corrected the remaining 20 papers and found the mean to be 80. This means the sum of the scores for her group is 20 x 80 = 1600.

Now, let's calculate the total sum of the combined group:
Total sum = sum of Tony's group + sum of Alice's group
Total sum = 700 + 1600 = 2300

Since there are 30 students in the combined group, we divide the total sum by 30 to find the mean:
Mean of the combined group = Total sum / Total number of students
Mean of the combined group = 2300 / 30 = 76.67 (rounded to two decimal places)

Therefore, the mean of the combined group of 30 students is approximately 76.67.