Big Ideas Math Integrated I, 2016
BI
Big Ideas Math Integrated I, 2016 View details
Chapter Test
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Exercise 8 Page 211

Practice makes perfect
a We are told that the first row has 42 seats and every row after has 3 more than the previous one. We can model this situation using a linear function in slope-intercept form, where the number of seats depends on the row number.

s(r)=mr+b The slope of our function will be equal to the increase of seats per row 3. s(r)= 3r+b In order to find b we will substitute the only point we know, ( 1, 42), into the function.

s(r)=3r+b
42=3( 1)+b
Solve for b
42=3+b
39=b
b=39

The function is s(r)=3r+39. Now we can calculate the number of seats in the 25th row.

s(r)=3r+39
s( 25)=3( 25)+39
s(25)=75+39
s(25)=114

There are 114 seats in the Row 25.

b We can find the row with 90 seats using the function from Part A.
s(r)=3r+39 Let's substitue 90 for s(r) and calculate r.

s(r)=3r+39
90=3r+39
Solve for r
51=3r
17=r
r=17

Therefore, there are 90 seats in the 17th row.