4. A zoo is open for 10 1/2 hours every day. There
are two security guards on duty at a time and each
shift is 3 1/2 hours. How many shifts are there per
day?
A. 1 shift
B. 2 shifts
C. 3 shifts
D. 4 shifts
This can come from process of elimination, 1 shift is not enough. 2 shifts, 3 1/2 + 3 1/2 is 7, meaning it still isn't enough. 4 shifts 7 + 7 is 14, making it to much.
