It takes 5 toothpicks to build the top trapezoid shown at right.
You need 9 toothpicks to build 2 adjoined trapezoids and 13 toothpicks for 3 trapezoids.
a. If 1000 toothpicks are available, how many trapezoids will be in the last complete row?
b. How many complete rows will there be?
c. How many toothpicks will you use to construct these rows?
d. Use the numbers in this problem to carefully describe the difference between a sequence and a series.