6. If each of eight biology classrooms is in use for 5 hours and 15 minutes per day, and total of 84 student experiments are done, how long does each experiment take on average?
A.20 minutes
B.30 minutes
C. 40 minutes
D.50 minutes
E.1 hour
please show work.
8 hrs, 15 minutes = 315 minutes
total minutes available for the experiments
= 8(315) = 2520 minutes
84 experiments take 2520 minutes
1 experiment takes 2520/84 or 30 minutes
To find out how long each experiment takes on average, you need to calculate the total amount of time spent in biology classrooms for all the experiments and then divide it by the total number of experiments.
In this case, there are 8 biology classrooms and each is used for 5 hours and 15 minutes (which is equivalent to 5.25 hours) per day. So, the total amount of time spent in biology classrooms per day is:
8 classrooms × 5.25 hours/classroom = 42 hours.
Now, we need to find out the total time spent on all the experiments. If 84 student experiments are done, and each experiment takes the same amount of time, we can multiply the number of experiments by the amount of time each experiment takes on average. Let's call the time for each experiment "x".
Total time spent on experiments = 84 experiments × x hours/experiment.
Since we already know that the total time spent on experiments is 42 hours, we can set up the equation:
42 hours = 84 experiments × x hours/experiment.
To solve for x, we can divide both sides of the equation by 84 experiments:
x hours/experiment = 42 hours / 84 experiments.
Simplifying the right side of the equation:
x hours/experiment = 0.5 hours/experiment.
Finally, we can convert 0.5 hours to minutes by multiplying it by 60:
x minutes/experiment = 0.5 hours/experiment × 60 minutes/hour.
x minutes/experiment = 30 minutes.
Therefore, each experiment takes an average of 30 minutes. So, the answer is option B) 30 minutes.