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CBSE Class 9 Answered

If the mean of 1,2,3,.........x is 6x/7 find the value of x
Asked by The All Purpose World v2.0 | 28 Jan, 2018, 01:10: PM
answered-by-expert Expert Answer
begin mathsize 16px style Sum space of space first space straight n space naturals space numbers space is space fraction numerator straight n open parentheses straight n plus 1 close parentheses over denominator 2 end fraction.
Hence space sum space of space first space straight x space natural space numbers space is space fraction numerator straight x open parentheses straight x plus 1 close parentheses over denominator 2 end fraction.
Mean space of space straight x space numbers space is space fraction numerator straight x open parentheses straight x plus 1 close parentheses over denominator 2 straight x end fraction equals fraction numerator straight x plus 1 over denominator 2 end fraction.
According space to space the space question
fraction numerator straight x plus 1 over denominator 2 end fraction equals fraction numerator 6 straight x over denominator 7 end fraction
7 straight x plus 7 equals 12 straight x
12 straight x minus 7 straight x equals 7
5 straight x equals 7
straight x equals 7 over 5 end style
Answered by Sneha shidid | 29 Jan, 2018, 10:11: AM
CBSE 9 - Maths
Asked by The All Purpose World v2.0 | 28 Jan, 2018, 01:10: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
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