Pennies made before 1983 are 97% copper and 3% zinc, whereas pennies made after
ID: 3022091 • Letter: P
Question
Pennies made before 1983 are 97% copper and 3% zinc, whereas pennies made after 1983 are 3% copper and 97% zinc. Listed below are the weights (in grams) of pennies from each of the two time periods. Find the mean and median for each of the two samples, then compare the two sets of results.
Before 1983:
3.1037
3.1587
3.1277
3.0777
3.1047
3.1083
After 1983:
2.4901
2.4848
2.4957
2.5025
2.4827
2.4997
The mean weight of the pennies made before 1983 is
nothing
grams.
(Round to five decimal places as needed.)
The median weight of the pennies made before 1983 is
nothing
grams.
(Round to five decimal places as needed.)
The mean weight of the pennies made after 1983 is
nothing
grams.
(Round to five decimal places as needed.)
The median weight of the pennies made after 1983 is
nothing
grams.
(Round to five decimal places as needed.)
Does there appear to be a considerable difference in the means?
A.
No, because the difference in the means is more than 5%.
B.
Yes, because the difference in the means is more than 5%.
C.
No, because the difference in the means is less than 5%.
D.
Yes, because the difference in the means is less than 5%.
Before 1983:
3.1037
Explanation / Answer
The mean weight of the pennies made before 1983 is
( 3.1047 + 3.1587 + 3.1277 + 3.0777 + 3.1047 + 3.1083)/6
= 3.11363 grams
The mean weight of the pennies made after 1983 is
( 2.4901 + 2.4848 + 2.4957 + 2.5025 + 2.4827 + 2.4997)/6
= 14.9555/6 = 2.49258 grams
The median weight of the pennies made after 1983 is
(3.1047 + 3.1083)/2 = 4.1065 grams
The median weight of the pennies made after 1983 is
(2.4901 + 2.4957)/2 = 3.4929
The mean difference is (3.11363 - 2.49258) = 0.62105
Yes because the difference in the means is more than 5%.
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