SOLUTION: 5. Harris had an investment that yielded the following results over the last 4 years: 10.0%; 7.0%; 13.5%; -12.0%. What is the arithmetic mean? The geometric mean?

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Question 1187335: 5. Harris had an investment that yielded the following results over the last 4 years:
10.0%; 7.0%; 13.5%; -12.0%.
What is the arithmetic mean? The geometric mean?

Found 2 solutions by MathLover1, ikleyn:
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

10.0%,7.0%,13.5%,-12.0%
to calculate arithmetic mean, write percentage as decimal, add all and divide by 4
arithmetic mean=%280.10%2B0.07%2B0.135-0.12+%29%2F4=0.04625 or 4.625%

geometric mean:
Geometric mean=sqrt%28product+_of+_the_+n_+data_+values%29, assuming+all data
values are positive
in your case ,0.10,0.07,0.135,-0.12+, geometric mean cannot+ be calculated
Geometric mean can only be calculated when all numbers have the same sign.
Geometric mean cannot be calculated for negative values.

Answer by ikleyn(52784) About Me  (Show Source):
You can put this solution on YOUR website!
.
Harris had an investment that yielded the following results over the last 4 years:
10.0%; 7.0%; 13.5%; -12.0%.
What is the arithmetic mean? The geometric mean?
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When the yield coefficients (the growing coefficients) of the account are given as the percentages,

from year to year, as in this given problem, which means


    r%5B1%5D = 1.10 in the 1st year;  r%5B2%5D = 1.07 in the 2nd year;  r%5B3%5D = 1.135 in the 3rd year;  r%5B4%5D = 0.88 in the 4th year,


then the geometric mean DENOTES the geometric mean of these groving coefficients  1.1, 1.07, 1.135 and 0.88.



It MAKES SENSE, since allows to measure / (to evaluate) the average effective annual growing coefficient over the four years.



This geometric mean of the growing coefficients obeys to the usual definition


    G(1.1, 1.07, 1.135, 0.88) = root%284%2C+1.1%2A1.07%2A1.135%2A0.88%29 = root%284%2C+1.17588%29 =  1.041271 = 1.04 (rounded).    ANSWER


The geometric mean growing coefficient, effective over the four years, is 1.04, and the average percentage yield is about 4%.

Solved, answered and carefully/thoroughly explained.

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See my lesson
    - WHAT IS Geometric mean
in this site.