1. Cell phone A charges at a rate of 33% every 30 minutes, which means it charges at a rate of 1.1% per minute (33%/30min = 1.1%/min).
Cell phone B's charging rate is not given for all times, but we can use the two data points in the table to estimate its charging rate.
From 0 to 12 minutes, the battery charges by 27%, which means it charges at a rate of 2.25% per minute (27%/12min = 2.25%/min). From 12 to 20 minutes, the battery charges by 18%, which means it charges at a rate of 1.5% per minute (18%/8min = 1.5%/min).
Therefore, cell phone B charges at a greater percentage rate than cell phone A between 0-12 minutes of being connected to the charger. After 12 minutes, cell phone A charges at a greater percentage rate than cell phone B.
2. Let's assume that cell phone B charges at a constant rate between 0-20 minutes. To find the charging rate, we can use the two data points in the table:
From 0 to 12 minutes, the battery charges by 27%. From 12 to 20 minutes, the battery charges by an additional 18%. So, in total, the battery charges by 45% in 20 minutes.
Using this information,
we can set up a proportion to find the time it will take cell phone B's battery to be 100% charged:
20min / 45% = x / 100%
Cross-multiplying, we get:
45x = 2000
Dividing by 45, we get:
x ≈ 44.44
Therefore, it will take approximately 44.44 minutes (rounded to the nearest hundredth) for cell phone B's battery to be 100% charged if it charges at a constant rate.