How do I interpret this statistic data?

[1g0tquestions]

The results of 100 students are given in the table below.

Find an estimate of the mean and standard deviation of the results.

Marks	Number of Students
30 < x <= 40	5
40 < x <= 50	8
50 < x <= 60	10
60 < x <= 70	18
70 < x <= 80	22
80 < x <= 90	24
90 < x <= 100	13

Can this question be interpreted by adding (31 + 32 + 33 + 34 + 35 + ..... + 100) / 71 = answer for mean?

*71 comes from counting from 31 to 100.

 

[Deleted member 4993]

The results of 100 students are given in the table below.

Find an estimate of the mean and standard deviation of the results.

Marks	Number of Students
30 < x <= 40	5
40 < x <= 50	8
50 < x <= 60	10
60 < x <= 70	18
70 < x <= 80	22
80 < x <= 90	24
90 < x <= 100	13

Can this question be interpreted by adding (31 + 32 + 33 + 34 + 35 + ..... + 100) / 71 = answer for mean? .... Incorrect

*71 comes from counting from 31 to 100.

This is not a uniform distribution!

If you plot the data above, you will get a histogram.

What have you been taught about analyzing data from a histogram?

 

[1g0tquestions]

This is not a uniform distribution!

If you plot the data above, you will get a histogram.

What have you been taught about analyzing data from a histogram?

Hi Subhotosh, thank you for replying.

None. I have not been taught on histogram.

How do I actually interpret this questions? Any pointers?

 

[Deleted member 4993]

Hi Subhotosh, thank you for replying.

None. I have not been taught on histogram.

How do I actually interpret this questions? Any pointers?

Do a google search with key-words "analyzing Histogram"

Study some of those - and come back to discuss with us if you do not understand something.

You do realize that we cannot help you understand/solve the problem from base 0.

You know how to calculate mean and standard deviations for a string of discrete numbers?

 

[Dr.Peterson]

The results of 100 students are given in the table below.

Find an estimate of the mean and standard deviation of the results.

Marks	Number of Students
30 < x <= 40	5
40 < x <= 50	8
50 < x <= 60	10
60 < x <= 70	18
70 < x <= 80	22
80 < x <= 90	24
90 < x <= 100	13

Can this question be interpreted by adding (31 + 32 + 33 + 34 + 35 + ..... + 100) / 71 = answer for mean?

*71 comes from counting from 31 to 100.

You might start by looking under Mean here: https://www.mathsisfun.com/data/frequency-grouped-mean-median-mode.html

Then look up standard deviation similarly.

What HAVE you learned about data like this?

 

[HallsofIvy]

Since you are given the number of values "between 30 and 40", "between 40 and 50", "between 50 and 60", etc. I would use the midpoints, 35, 45, 55, etc. rather than 31, 41, 51 that you suggest.