Word problems- probability

[rachelmaddie]

I need my work checked please.

Known:
Points: 50 75 150
Frequency: 55 32 13

Expected value of a random variable is its mean value. Find the mean value of points earned per turn from the table given.
Total number of turns = sum of frequencies
—> = 55 + 32 + 13 = 100
Total points earned = 50(55) + 75(32) + 150(13) = 7100

Expected value of points earned for a turn = Mean value of points = Total points/no. of turns
—> 7100/100 = 71
Solution: The game’s expected value of points earned for a turn is 71.

 

[Steven G]

The expected value is 50(.60) + 75(.30) + 150(.10) = 30 + 22.5 + 15 = 67.5

Why are you using the numbers from the table?

 

[rachelmaddie]

The expected value is 50(.60) + 75(.30) + 150(.10) = 30 + 22.5 + 15 = 67.5

Why are you using the numbers from the table?

I don’t understand how did you get that?

 

[Steven G]

I don’t understand how did you get that?

The numbers were given in the problem!
It says that the probability of scoring 50 points is 60%, 75 points is 30% and 150 points is 10%.

The problem in my opinion is worded terribly.

 

[rachelmaddie]

The numbers were given in the problem!
It says that the probability of scoring 50 points is 60%, 75 points is 30% and 150 points is 10%.

The problem in my opinion is worded terribly.

Okay. Then divide that value by 100?

 

[HallsofIvy]

No, that's not Jomo's point. In your first post you had

View attachment 20615

Those are two conflicting statements! In the words it says that the probability of 50 points is 60%, not the 55% you get from the "frequency" in table. And the probability of 75 points is, according to the words, 30%, not the 32% from the "frequency". And the probability of 150 points is 10%, not 13%.

 

[rachelmaddie]

No, that's not Jomo's point. In your first post you had

Those are two conflicting statements! In the words it says that the probability of 50 points is 60%, not the 55% you get from the "frequency" in table. And the probability of 75 points is, according to the words, 30%, not the 32% from the "frequency". And the probability of 150 points is 10%, not 13%.

Can you show me? I’m getting confused.

 

[Steven G]

Can you show me? I’m getting confused.

You can show yourself. In the words it has one set of probabilities and in the table under frequency it has another set of numbers. Just read the problem and you'll see for yourself.

 

[Steven G]

Okay. Then divide that value by 100?

No.

 

[rachelmaddie]

No.

Expected value of a random variable is its mean value. Find the mean value of points earned per turn from the table given.

The expected value is 50(.60) + 75(.30) + 150(.10) = 30 + 22.5 + 15 = 67.5

How is this?