If the ratio x: y:z is 3:5:7, what is the value of z?
(1) The average (arithmetic mean) of x, y, and z is 25.
(2) The value of x is 15.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
OFFICIAL ANSWER IS NOT PROVIDED.
x:y:z = 3:5:7
means x=3k, y=5k, z=7k where k is the common value in all the three numbers.
(x+y+z)/3 = 25
x+y+z = 75
=> 3k + 5k+ 7k = 75
15k = 75
k = 5
z = 7k = 35
=> 3k = 15
=> k =5
=> z = 7k = 7*5 = 35
Answer will be D
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