Algebra 1 Common Core Student Edition, Grade 8-9

Go t I t? 2. What is each product?

a. -2 [ —3 7.1 5] b. 1.5

-11

0

3

-1.5

You can use matrices to organize real-world data.

Using M atrices

Weather Use the weather chart below. Which city has the greatest average number

of clear days in a full year?

Average Number of Clear and Cloudy Days

Sep t em b er- Feb ruary M arch- August

P h o e n ix : 102 clear, 41 c lo u d y P h o e n ix : 110 clear, 27 c lo u d y

M ia m i: 4 3 clear, 5 8 c lo u d y M ia m i: 31 clear, 5 9 c lo u d y

Portland: 55 clear, 82 cloudy Portland: 45 clear, 83 cloudy

Po r t l an d , ME

Ph o en i x , AZ

Miami, FL

What size m at r ices
sh o u l d y o u u se?
There are three cities and
tw o types of weather
represented by the data.
So you can use
3 x 2 matrices or
2 x 3 matrices.

St e p 1 Use matrices to organize the information.

Se p t e m b e r - Fe b r u a r y

Clear Cloudy

March-August

Clear Cloudy

Phoenix "102 41' Phoenix "110 27 ”

Miami 43 58 Miami 31 59

Portland 55 82. Portland _ 45 83

"102 41" ~110 27 ~ 212 68 "

43 58 + 31 59 =^74117

55 82 _ 45 83 _ 100 165 _

St e p 2 Add the matrices to find the average numbers of clear and cloudy days in a full

year for each city. The matrices are the same size, so you can add them.

Add

corresponding

elements.

St e p 3 Find the greatest average number of clear days in a full year. Ihe first

column of the matrix represents the average number of clear days in a

full year for each city. Ihe greatest number in that column is 212, which

corresponds to Phoenix. So Phoenix has the greatest average number of

clear days in a full year.

& Got It? 3. Which city in Problem 3 has the greatest average number of cloudy days

in a full year?

212 68

74 117

100 165

728 Ch ap t er 12 Data Analysis and Probabilit y