4. A fruit shop received a batch of apples. On the first day, it sold half of the half. On the second day, it sold half of the remaining apples. On the third day, it sold all the remaining 15 kilograms of apples. The total weight of the batch of apples the fruit shop received is ( ) kilograms.
40
【Answer】 40 ; the remaining on the second day is half, which is 15 ; this means the remaining on the first day was 30 ; on the first day, one quarter was sold; thus, three quarters were left, which is 30 ; hence, the initial total was 40