Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

A fair die is rolled twenty times. The results are shown in the bar graph. What is the mean score for the $20$ rolls?

enter image description here

share|improve this question
2  
"mean" is just a fancy word for "average". What do you know about computing the average of a bunch of numbers? –  Gerry Myerson Jun 18 '13 at 13:50
    
I don't will you please guide me . –  SSK Jun 18 '13 at 14:06
1  
It seems from your comment on one of the answers that you do know something about computing the average of a bunch of numbers. Good on ya. –  Gerry Myerson Jun 19 '13 at 9:04
    
(homework) should not be used as a standalone tag; see tag-wiki and meta. –  Martin Sleziak Jun 19 '13 at 10:20

3 Answers 3

up vote 5 down vote accepted

You have three 1s, one 2, five 3s, one 4, four 5s and six 6s so you want to find the mean (average) of

$$\{1,1,1,2,3,3,3,3,3,4,5,5,5,5,6,6,6,6,6,6\}.$$

As Gerry Myerson essentially asked, can you find the average of these numbers?

share|improve this answer
3  
my pleasure , $1+1+1+2+3+3+3+3+3+4+5+5+5+5+6+6+6+6+6+6/20 = 4$ –  SSK Jun 18 '13 at 14:16
    
Boom. This is where Abhra's formula comes from and is exactly what gt has although I wasn't sure if you understood the sigma notation; the $\sum$ just means 'add up'. –  Jp McCarthy Jun 18 '13 at 14:59

Hint: Mean $\displaystyle =\frac{\sum_{\text{over all score}} [\text{(frequency) }\times score]}{\sum_{\text{over all score}} \text{(frequency) }}$

share|improve this answer

Hint Write down (using the graph) how many rolls of each score happened. In total, you wil now know which scores $x_1,\ldots,x_{20}$ were rolled in the 20 rolls.

Now find the arithmetic mean $\frac{1}{20} \sum_{k=1}^{20} x_k$ and it will be your mean score.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.