Measures of Central Tendency Pretest 2

Question 2

2.The mean mark on 4 tests is 78%. What mark is needed on the next test to increase the mean to 80%?

The mean mark of 4 tests is 78%
4 x 78 = 312
So 312 is considered the sum of all data for data set 1.

We need to get an 80% average and now we have done another test so, 80 x 5(# of tests) = 400
400 is considered the sum of all data for data set 2.

Now we subtract the two sums of data from each other
The difference between the two sums of data is ..
400 - 312 = 88

So 78+78+78+78+88= 400/5 = 80(%)

88% is needed to increase the mean to 80%.


-masesar