By what percent is a 100-watt light bulb brighter than a 60-watt light bulb? (Round percent to the nearest tenth.

To find the percentage difference in brightness between a 100-watt light bulb and a 60-watt light bulb, we can use the formula:

Percentage difference = (New value - Old value) / Old value * 100

In this case, the new value is 100 watts and the old value is 60 watts. Plugging these values into the formula, we get:

Percentage difference = (100 - 60) / 60 * 100
Percentage difference = 40 / 60 * 100
Percentage difference = 0.6667 * 100
Percentage difference = 66.67

Therefore, the 100-watt light bulb is approximately 66.7% brighter than the 60-watt light bulb.