Solve: (i)25 + 22 + 19 + 16 + ... + x = 115 (ii) 1 + 4 + 7 + 10 + ... + x = 590
In this 100 surnames were randomly picked up from a local telephone directory and the frequency distribution of the number of letters in English alphabets in the surnames was obtained as follows: Determine the number of median letters in the surnames. Find the number of mean letters in the surnames and also, find the size of modal in the surnames.
Number of letters
1-4
4-7
7-10
10-13
13-16
16-19
Numbers of surnames
6
30
40
16
4