The mean is equal to (7.5x2+12.5x6+20x10+30x22+42.5x27+55x11)/(2+6+10+22+27+11)=34.6474359

The mode is 35+(5x15)/(5+16) = 38.57143

The median is 25+(39-18)x10/22 = 34.5455

@Ette Etuk

Thank you so much for your answer

@Wulf Rehder

Thank you so much for your clarification and valuable answer, I highly appreciate your efforts.

Please refer to:

1. Landau, S. and Everitt, B. S.(2004). A Handbook of Statistical analyses using SPSS.

2.Howitt, D. and Cramer, D.(2008). Introduction to SPSS.

Regards,

Zuhair

Dear Deeman Yousif Mahmood ,

You first prepare a discrete frequency distribution table taking the mid values of the class intervals as the values assumed by the variable.

Then apply the the usual formula for mean to get the value of mean.

For computing median and mode, prepare a cumulative frequency distribution table. Then apply the usual formulas/methods. The formulas/methods are available in any standard book on Mathematical Statistics.

Dear Deeman Yousif Mahmood,

Please refer to the following link for detailed explanation on calculating the mean, mode and median for grouped data.

https://www.youtube.com/watch?v=nfxYEOl8n0w

https://www.mathsisfun.com/data/frequency-grouped-mean-median-mode.html

https://www.universalclass.com/articles/math/statistics/how-to-calculate-mean-median-mode.htm

http://ncert.nic.in/NCERTS/l/jemh114.pdf

https://statistics.laerd.com/spss-tutorials/three-way-anova-using-spss-statistics.php

Regards

Vishwanatha

Using a software like Minitab will simply solve this issue.

Calculate the mid value of each of the class intervals.

Suppose the mid values are

X1 , X2 , X3 , ............ , Xn.

Suppose, the corresponding frequencies are

f1 , f2 , f3 , ............... , fn.

Then mean is to be calculated by the formula

(f1,X1 + f2.X2 + ............. + fn.Xn)/(f1 + f2 + ........... + fn)