Problem:
A rectangular field is 300 feet wide and 400 feet long. Random sampling indicates that there are, on the average, three ants per square inch throughout the field. [12 inches =1 foot.] Of the following, the number that most closely approximates the number of ants in the field is
Answer Choices:
A. 500 thousand
B. 5 million
C. 50 million
D. 500 million
E. 5 billion
Solution:
The number of ants is approximately the product
(300ft)×(400ft)×(12in/ft)2×(3 ants /in2)=300×400×144×3 ants,
which is 3×4×1.44×3×102+2+2≈50×106.