Lithium batteries are used to power laptops. When not in use, a lithium battery (like all batteries) loses a small amount of energy. At 30°C, the b...

Lithium batteries are used to power laptops. When not in use, a lithium battery (like all batteries) loses a small amount of energy. At 30°C, the battery loses 3% of its charge every day. How much of its original charge will be lost after this temperature? It is easy to estimate. If 3% is lost every day, then in seven days, approximately 21% of the charge is lost. Therefore, the battery will have about 79% of its original charge. The correct answer is 80.8%, which is slightly higher than the estimate: At the end of the first day, 97% = 0.97 of the original charge remains. At the end of the second day, 97% of the 97% or 0.97 * 0.97 or 94.09% remains. At the end of the third day, 97% of these 94.09% = 91.27%. So, at the end of the week, 80.8% of the charge still remains in the battery. The graph that represents the battery's charge loss is:


Gráfico I
Gráfico II
Gráfico III