Question

A student needs to make a circular cardboard piece with an area between 154 square inches and 616 square inches. The function f(r) relates the area of the cardboard piece, in square inches, to the radius r in inches. Which of the following shows a reasonable domain for f(r)?
A) 7 < r < 14
B)154 < r < 616
C) all positive integers less than 7
D) all positive integers between 14 and 154

Question 35 (Multiple Choice Worth 1 points)

(04.02)

An expression is shown below:

square root of 18 plus square root of 2

Which statement is true about the expression?

A) It is rational and equal to 3.
B)It is rational and equal to 4.
C)It is irrational and equal to 3 multiplied by the square root of 2.
D) It is irrational and equal to 4 multiplied by the square root of 2.

Answer 1

Given:
circular cardboard with an area between 154 in² and 616 in²

Area of a circle = πr²
154 in² = 3.14 * r²                     616 in² = 3.14 * r²
154 in² / 3.14 = r²                      616 in² / 3.14 = r²
49 in² = r²                                  196 in² = r²
√49 in² = √r²                             √196 in² = √r²
7 = r                                          14 in = r

Radius is between 7 inches and 14 inches. ⇒ A) 7 < r < 14

√18 + √2 = √9 *2 + √2 = 3√2 + √2 = (3+1) √2  = 4√2

D) It is irrational and equal to 4 multiplied by the square root of 2.