Anew restaurant with 149 seats is being planned. studies show that 61% of the customers demand a smoke-free area. how many seats should be in the non-smoking are in order to be very sure of having enough seating there?

You would want to have more than 61% of the seats available for a smoke free area.

61% = 0.61     0.61 * 149 = 90.89 or 91 seats to accommodate 61% smoke free customers

To allow for any extra customers in a smoke free area I would figure on 65%

so 65% = 0.65       0.65 * 149 = 96.85  or 97 seats to allow for a few extra for the customers in the smoke free area