Dunn Co. sold equipment service contracts that cover a two year period. the sales price of the contract is $600. Dunne's past experience is that, of the total dollars spend for repairs on service, 40% is incurred evenly during the first contract year and $60% evenly during the second year. In its December 31 balance sheet, what amount should Dunne report as deferred service contract revenue.

My answer: ok I through that since 40% of total dollars spent incurred evenly (which means through the whole year according to my understanding), then on December 31, 40% of the $600 is recognized revenue. and 60% of the $600 ($360) is unearned revenue.

The answer in Becker book: since repairs are made evenly (july 1 is average date), only 1/2 of the 40% of repairs will be in the current year. so 600x40%x1/2 = 120 earned in the current year, and the remaining $480 is deferral.

I don't understand why they multiply by 1/2 , why july 1, can someone explain please