178 people people were asked coins they had in their pockets and the following results were obtained: No. of coin: 0-4, 5-7, 8-10, 11-12 No. of people: 6, 8, 8

178 people people were asked coins they had in their pockets and the following results were obtained:

No. of coin: 0-4, 5-7, 8-10, 11-12
No. of people: 6, 8, 8, 8.

Find the mean number of coins​