Question

Find the average mean?
http://prnt.sc/dk06yu

Answer 1

@3mar i know how to find the average (mean) but im not sure how on this one because the results never match up with the answer options.

Answer 2

What do you think?

Answer 3

2 - 2.5 was the closest number i was getting

Answer 4

@3mar i added all the numbers (equaling 1) and found the average (divided by 5) and the result was 0.2. Then i found the average of just the ones who HAD siblings and left out 0. But it still wasnt right

Answer 5

"Then i found the average of just the ones who HAD siblings and left out 0."

What so you mean by that?

Answer 6

What do x and p(x) stand for?

Answer 7

i didnt include the decimal of those who did not have siblings

Answer 8

good idea
multiply and add

Answer 9

multiply what?

Answer 10

the probabilities by the numbers

Answer 11

\[1\times 0.6+2\times 0.05+3\times 0.15+4\times 0.1\]

Answer 12

@satellite73 1.55 - would it mean B or C?

Answer 13

dunno
i cannot read the mind of the person who made the question, but given the \(4+\) at the end of the table, i would round up

Answer 14

i would not bet more than $7 on that answer though

Answer 15

Does it tell you anything that the greatest probability by far is 0.6? Under what number (of siblings) do you find that? Notice the prob. to the left of 0.6 is 0.1 and that to the right of 0.6 is 0.05. What do you suppose the graph of these probabilities would look like? Would it be possible to infer the mean of all this data just by looking at the given table or the graph that you would draw?

Answer 16

i dont know, ill try

Answer 17

@mathmale i did but i dont think it means anyhting

Answer 18

is it not clear how to do this?

Answer 19

if not that is fine, tell me and i will show you how to do it

Answer 20

i found the average, though i guess not the right way because i cant get the correct result. So yeah if you could thatd be great

Answer 21

ok lets imagine that there are 100 students in the class

Answer 22

There is a simple procedure for finding the average value; it consists of multiplying each possible sibling count (0, 1, 2, .. ) by the probability that appears underneath each such count. Then you add the products together. Unfortunately, that 4+ creates a problem, since that 4+ could represent 4, 5, 6, 7, ...

On the other hand... the value 1 appears many times more often than does any other value. Seems to me that that tells us immediately that the average number of siblings is 1 or very close to 1.

Answer 23

i messed up
it is \[1\\
0.6\] so \(60\%\) of the students have on sibling

Answer 24

what is \(60\%\) of 100? (don't think too hard)

Answer 25

3/5 = 0.6

Answer 26

yeah i was asking what \(60\%\) of 100 was, not what .6 is as a decimal

Answer 27

i see the problem
i just computed it and got 1.55 too, which is not an answer choice
so you have to choose between 1.5 and 2

Answer 28

i.e. round up or down
like i said, i would round up but that is just a guess

Answer 29

exactly, thats where im at

Answer 30

thank you @satellite73 and @mathmale