Carcass wrote:
If the average (arithmetic mean) of the four numbers M, 2M − 1, 3M + 5, and 5M − 3 is 25, what is the value of M?
(A) 2 2/11
(B) 4
(C) 8
(D) 9
(E) 9 1/11
Kudos for the right answer and explanation
Question part of the project GRE Quant/Math Extreme Challenge Daily (2021) EditionGRE - Math Book The average (arithmetic mean) of the four numbers M, 2M − 1, 3M + 5, and 5M − 3 is 25We can write: \(\frac{(M) + (2M − 1)+ (3M + 5)+(5M − 3)}{4} = 25\)
Simplify numerator: \(\frac{11M+1}{4} = 25\)
Multiply both sides by 4 to get: \(11M+1 = 100\)
Subtract 1 from both sides: \(11M = 99\)
Solve: \(M = 9\)
Answer: D