06-05-2014, 08:46 AM
How do we solve for a mean for a set if we know the value for each member in the set? With two steps:
1. value for member 1 + value for member 2 + ⦠= sum of values
2. sum of values / number of members in the set = mean
In this question, we aren't given the values for individual members of any of the sets. But because we have the means of each set, we can do step 2 backwards to get the sum of values for each set.
Because
sum of values / number of members = mean
therefore
mean * number of members = sum of values
And that "sum of values" for the first set described is
(10 numbers * 40)
for the second set described is (30 numbers * 60), and for the third set described is (60 numbers * unknown).
1. value for member 1 + value for member 2 + ⦠= sum of values
2. sum of values / number of members in the set = mean
In this question, we aren't given the values for individual members of any of the sets. But because we have the means of each set, we can do step 2 backwards to get the sum of values for each set.
Because
sum of values / number of members = mean
therefore
mean * number of members = sum of values
And that "sum of values" for the first set described is
(10 numbers * 40)
for the second set described is (30 numbers * 60), and for the third set described is (60 numbers * unknown).
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