Explanation:
24. A
B' ( t ) = 10 [ 20 CDS ( t/10) ] = 2 COS ( t/10 )
B' ( 7 ) = 1.5
After 7 days the number of beds in use is increasing at the rate of 1 1/2 beds per day.
24.B
2 COS ( t/10) =0
using calculator t = 15.7
B (12) = 20 Sin (1.2) + 50 = 68.6 = 69
B (15.7) = 20 Sin (1.57) + 50 = 70
B (20) = 20 SIn (20) + 50 = 68.25 = 68
Maximum number of beds in use occurs in afternoon of 15th day and is 70 beds.
I hope that helps and I hope it's right