20. The mean of 25 observations is 36. Out of these observations if the mean of first 13 observations is 32 and that of the last 13 observations is 40, the 13th observation is : 20. The mean of 25 observations is 36. Out of these observations if the mean of first 13 observations is 32 and that of the last 13 observations is 40 the 13th observation is : July 3, 2021 Category: Chapter 14 - Statistics , Chapter 15 - Probability , Maths , NCERT Class 9 , Facebook Messenger WhatsApp Share this:TwitterFacebook Related