Find the annual percent increase or decrease that y

Can you check my answers and if wrong, please explain! Thanks!

  1. Find the annual percent increase or decrease that y = 0.35(2.3)^x models.

A. 230% increase B. 130% increase C. 30% decrease D. 65% decrease

My answer was A. 230% increase

2 Answers

  • I believe you are right.

    If x measures time (in years) then the value of y this year is 0.35·2.3^x, and next year it's 0.35·2.3^(x+1)

    0.35·2.3^x · /annual increase/ = 0.35·2.3^(x+1)

    2.3^x · /annual increase/ = 2.3^(x+1)

    /annual increase/ = 2.3^(x+1) / 2.3^x

    /annual increase/ = 2.3 = 230%

    edit. I think Ed I is right, but I'm not really familiar with the exact meaning of this term (in english).

    1+/annual increase/ = 2.3

    /annual increase/ = 1.3 = 130%

  • The percent of increase is the amount over 100%, i.e. 130%.

    B

    Source(s): I have taught for over 40 yr.

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