Transfer rate is 1KBps , So 1KB----------1 s (second)
1 Byte-------1/1000 s
16 Bytes-----16/1000 = 16ms
Also ,it is given that the DMA controller requires 10 cycles for initialization of operation and transfer takes 2 cycles to transfer one byte of data from the device to the memory.
Therefore , to transfer 16 bytes cycles needed = 16*2=32 cycles , So total cycles needed is 32+10 = 42 cycles
Transfer Time = 42 * 1/400000 = 42/400 ms = 0.105 ms
Now , %age of CPU blocked state is (Transfer time/Preparation time) *100 = 0.105 / 16 *100 = 0.65