psm12se wrote:Julie is putting M marbles in a row in a repeating pattern: blue, white, red, green, black, yellow, pink. If the row begins with blue marble and ends with red marble, then which of the following could be the value of M?
A. 22
B. 30
C. 38
D. 46
E. 54
A: C
Let's list a few and look for a PATTERN:
Marble 1: blue
Marble 2: white
Marble 3: red
Marble 4: green
Marble 5: black
Marble 6: yellow
Marble 7: pink
Marble 8: blue
Marble 9: white
Marble 10: red
Marble 11: green
Marble 12: black
Marble 13: yellow
Marble 14: pink
Marble 15: blue
Marble 16: white
Marble 17: red
.
.
.
As you can see, the position of the red marble is 3
plus some multiple of 7
In other words, the position of the red marble will equal
7n + 3
Since answer choice [spoiler]C (38)[/spoiler] can be written as
7(5) + 3, it must be the correct answer.
Cheers,
Brent
