Carcass wrote:
The average (arithmetic mean) of 17 numbers is ๐. If two of the numbers are ๐ and ๐, what is the average of the remaining 15 numbers in terms of ๐, ๐ and ๐?
A. \(\frac{k+m}{17}\)
B. \(17j+k+m\)
C. \(\frac{16j-k-m}{17}\)
D. \(\frac{17j-k-m}{15}\)
E. \(\frac{17(k-m)-j}{15}\)
Let F = the sum of the 15 numbers that
don't include k and m
So, the average of the 15 numbers \(= \frac{F}{15}\)
The average (arithmetic mean) of 17 numbers is j.We can write: \(\frac{F + k + m}{17} = j\)
What is the average of the remaining 15 numbers in terms of j, k and m? Take: \(\frac{F + k + m}{17} = j\)
Multiply both sides of the equation by 17 to get: \(F + k + m= 17j\)
Subtract k and m from both sides: \(F= 17j - k - m\)
Divide both sides by 15: \(\frac{F}{15}= \frac{17j - k - m}{15}\)
Answer: D