Mathematics

Question

Mark charged a battery. Each minute, the percentage of the battery's capacity that was charged increased by 2.5 percent. After 17 minutes of charging, the battery was 61.5 percent full. How full was the battery when the charging began

2 Answer

  • I'm not sure if this is correct but I made this into the equation 61.5=17+2.5x. I solved the equation and the answer I got is 17.8%
  • Answer: The battery was 19 percent full when the charging began.

    Step-by-step explanation:

    Since we have given that

    Every minute, the percentage of the battery's capacity increased by = 2.5%

    As we know that "Equation of line ":

    [tex]y=mt+b\\\\Here, \\\\\text{ 't' represents number of minutes and 'b' represents initial battery }[/tex]

    So, our equation becomes for now,

    [tex]y=2.5t+b[/tex]

    As we have given that,

    After 17 minutes, the battery was 61.5% full.

    So, our coordinate becomes (17,61.5)

    So, it becomes

    [tex]61.5=2.5\times 17+b\\\\61.5=42.5+b\\\\61.5-42.5=b\\\\19=b[/tex]

    Hence, the battery was 19 percent full when the charging began.

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