Question

11
a scientist studying the life cycle of butterflies counted the number of butterflies in a certain habitat each day for 46 days. on june 15, there were 168 butterflies in the habitat. the percent increase in the number of butterflies in the habitat from may 1 to june 15 was 31.25%. how many butterflies were in the habitat on may 1?
a 128
b 116
c 53
d 5

Explanation:

Step1: Define variable for May 1 count

Let \( x = \) number of butterflies on May 1.

Step2: Set up percentage increase equation

June 15 count = \( x + 31.25\%x = x(1 + 0.3125) = 1.3125x \)

Step3: Solve for \( x \)

\( 1.3125x = 168 \) → \( x = \frac{168}{1.3125} = 128 \)

Answer:

A. 128