Question

If a # b is defined as the average of a and b, what is the value of 2 # 4 # 9?
(a) 3
(b) 5
(c) 6
(d) 7.5
(e) 18

Answer 1

wont it just be the average of those three?

Answer 2

\[\huge \frac{2 + 4+ 9}{3}\]

Answer 3

the average is a+b+c/3 so it's 2+4+9/3= 5... but that's not the answer choices what's b?

Answer 4

sorry i didn't notice that my answer choices came out weird but thanks. i didn't think it was going to be that simple but i guess it is.

Answer 5

no problem! :D

Answer 6

although I thought an alternative solution would be finding average of 2 and 4 then using that answer to find the solution between that and 9... but maybe I'm overthinking it loll if we do it that way then it's c

Answer 7

yeah that's what i tried doing first

Answer 8

hmm that can be it... idk how difficult is the problem supposed to be if it was really easy I would pick 5 but if it's supposed to be hard then I would pick 6

Answer 9

yeah it's an sat question. sometimes they're really easy and other times they're really hard but i think i'm gonna stick to c.

Answer 10

lets try it

Answer 11

average of 2 and 4 is 3
average of 3 and 9 is 6

Answer 12

Loll I knew it was an SAT question , I was just about to ask you that.. is it the beginning of the test or at the end?

Answer 13

beginning lol

Answer 14

oh haha well it's supposed to be easy. But yeah c would be your best choice

Answer 15

yeah

Answer 16

now maybe we try it the other way
average of 4 and 9 is 6.5
average of 2 and 6.5 is 4.25
so i guess this is not associative
it matters what you do first

Answer 17

yeah i think so and that's not an answer choice either