Difference between revisions of "2006 iTest Problems/Problem 2"
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==Solution== | ==Solution== | ||
− | The [[harmonic mean]] of two numbers is the reciprocal of the mean of the reciprocals of the two numbers. The reciprocals of <math>10</math> and <math>20</math> are <math>\tfrac1{10}</math> and <math>\tfrac1{20}</math> and the mean of the two is <math>\tfrac3{40}</math>, so the harmonic mean is <math>\boxed{\textbf{(B) } \tfrac{40}{3}}</math> | + | The [[harmonic mean]] of two numbers is the reciprocal of the mean of the reciprocals of the two numbers. The reciprocals of <math>10</math> and <math>20</math> are <math>\tfrac1{10}</math> and <math>\tfrac1{20}</math> and the mean of the two is <math>\tfrac3{40}</math>, so the harmonic mean is <math>\boxed{\textbf{(B) } \tfrac{40}{3}}</math>. |
==See Also== | ==See Also== | ||
{{iTest box|year=2006|num-b=1|num-a=3|ver=[[2006 iTest Problems/Problem U1|U1]] '''•''' [[2006 iTest Problems/Problem U2|U2]] '''•''' [[2006 iTest Problems/Problem U3|U3]] '''•''' [[2006 iTest Problems/Problem U4|U4]] '''•''' [[2006 iTest Problems/Problem U5|U5]] '''•''' [[2006 iTest Problems/Problem U6|U6]] '''•''' [[2006 iTest Problems/Problem U7|U7]] '''•''' [[2006 iTest Problems/Problem U8|U8]] '''•''' [[2006 iTest Problems/Problem U9|U9]] '''•''' [[2006 iTest Problems/Problem U10|U10]]}} | {{iTest box|year=2006|num-b=1|num-a=3|ver=[[2006 iTest Problems/Problem U1|U1]] '''•''' [[2006 iTest Problems/Problem U2|U2]] '''•''' [[2006 iTest Problems/Problem U3|U3]] '''•''' [[2006 iTest Problems/Problem U4|U4]] '''•''' [[2006 iTest Problems/Problem U5|U5]] '''•''' [[2006 iTest Problems/Problem U6|U6]] '''•''' [[2006 iTest Problems/Problem U7|U7]] '''•''' [[2006 iTest Problems/Problem U8|U8]] '''•''' [[2006 iTest Problems/Problem U9|U9]] '''•''' [[2006 iTest Problems/Problem U10|U10]]}} |
Latest revision as of 02:24, 27 November 2018
Problem
Find the harmonic mean of 10 and 20.
Solution
The harmonic mean of two numbers is the reciprocal of the mean of the reciprocals of the two numbers. The reciprocals of and are and and the mean of the two is , so the harmonic mean is .
See Also
2006 iTest (Problems) | ||
Preceded by: Problem 1 |
Followed by: Problem 3 | |
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