To find out how many sixth graders will attend the morning assembly, we need to calculate 60% of the 90 sixth graders.
First, convert the percentage to a decimal:
60% = 0.60
Now, multiply 0.60 by 90:
0.60 × 90 = 54
So, 54 sixth graders will be at the morning assembly.
The correct answer is B. 54.