Question:

The pirce of a CD is denoted by $x. For 60CDs bought in different stores it is found that . Calculate the mean price of these CDs. The mean price of a further 40 CDs is found to be $11.64. The mean price of the 100 CDs.

Attempt:

Mean of 100 CDs =

The mean for 60 CDs is correct! but for 100 CDs is wrong. Where did I do wrong?