Compared to yesterday, you did three times the work in one-third the time. To do so, your power output must have been a. the same as yesterdays power output
b. one-third yesterdays power output
c. three times yesterdays power output
d. nine times yesterdays power output

D. nine times yesterdays power output

Explanation:

We know that formula for power with work is;

Power = workdone/time taken

Now, you did three times the work in one-third the time yesterday.

This means that;

Work yesterday; W_yesterday = W

Work today; W_today = 3W

Time yesterday; T_yesterday = t

Time today; T_today = t/3

Thus,power today is;

P_today = 3W/(t/3)

P_today = 9(W/t)

Since power output yesterday is W/t, it means you did nine times yesterday's power output.

the answer is b ) square root of 5