The given distribution in tabulated form is
We have to find the value of p using the information that the mean of the distribution is 7.68.
Prepare the following frequency table of which the first column consists of the values of the variate and the second column the corresponding frequencies. Multiply the frequency of each row with the corresponding values of variable to obtain the third column containing.
Find the sum of all entries in the second and third column to obtain N and respectively. Therefore,
The mean is
Hence, we have