In problems I and 2, compute the amount of (a) ordinary simple interest and (b) exact simple interest. Then compute (c) the difference between the two interest amounts. Ordinary Exact Principal Rate Time Interest Interest Difference 1 $1,680 6% 270 Days b. C. 2 $10,500 8% 60 Days h. C. In problems 3 and 4, first compute (a) the actual exact simple interest. Then, change each rate and time to the closest numbers that permit use of the shortcuts shown in Table 13-1 and compute (b) the estimated amount of exact interest. Finally, compute (c) the difference between the actual and estimated exact interest. Actual Estimated Principal Rate Time Exact Interest Exact Interest Difference 3 $12,000 3.8% 92 Days i. h. C. 4 $2.000 9.2% 117 Days h. C