Bell work The total number of students out for a fall

sport is 204 in our school of 1900 total students. What is the ratio of athletes to total students?

What is the ratio of athletes to non-athletes?

STUDENTS WILL BE ABLE TO SOLVE A PROPORTION, DEFINE A RATIO AND REDUCE THE RATIO TO SIMPLEST TERMS.

7.1 Proportions

Ratio (Defn) A comparison of two quantities.

Please note: A ratio can be written in 3 different

ways.

Ratios can (and should) be reduced.

Example 1 In a triangle, the ratio of the

measures of three sides is 5:12:13, and the perimeter is 90 cm. Find the measure of the shortest side of the triangle.

Example 2 A 2x4 piece of wood is 48 feet

long. If it is divided into two lengths in the ratio of 1:3, how long is the longer piece?

Proportion (Defn) An equation stating that two ratios are equal.

Cross-products of ratios are equal.

4 85 10

Example 3 Solve.

38 24

y

Example 4 Solve.

2 8 58 4x x

Example 5 A twinjet airplane has a length of 78 m

and a wingspan of 90 m. A scale model is made in proportion to the real airplane. If the wingspan of the scale model is 36 cm, find the length of the toy.

Ticket to Leave

Solve.

3 1 52 4x x

Homework Pg. 383 # 8, 11-13, 17, 18 – 26

evens, 47, 52, 57, 58