Pearson Algebra 2 Common Core, 2011
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Pearson Algebra 2 Common Core, 2011 View details
Cumulative Standards Review

Exercise 10 Page 493

I

Practice makes perfect

We are given a system of equations where x represents the number of servers and y represents the number of bus persons. 25 x+8 y=249 & (I) x+ y=12 & (II) To determine which of the given options is true, we will solve this system.

Solving the System

Let's use the Substitution Method. The Substitution Method is usually a good choice when one of the variables is already isolated or has a coefficient of 1. First we will isolate the y-variable in Equation (II). 25x+8y=249 x+y=12 ⇔ 25x+8y=249 y=12-x Next we will substitute 12-x for y in Equation (I) and solve it for x.
25x+8y=249 y=12-x
25x+8( 12-x)=249 y=12-x
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(I):Solve for x
25x+96-8x=249 y=12-x
17x+96=249 y=12-x
17x=153 y=12-x
x= 9 y=12-x
Now we can use that x= 9 to solve for y in Equation (II).
x=9 y=12-x
x=9 y=12- 9
x= 9 y= 3
We have that on the given night the company employs 9 servers and 3 bus persons.

Determining the Correct Option

Let's go through the statements one by one and determine if they are correct or not.

  • F: Fewer than 2 bus persons were working. There were 3 bus persons working that day, which is more than 2. The statement is incorrect.
  • G: More than ten servers were working. We have found that the number of servers working were 9, which is fewer than 10. The statement is incorrect.
  • H: 50 % of the people working were bus persons. Of the 12 people working, only 3 were bus persons, which is less than half. This statement is also incorrect.
  • I: 75 % of the people working were servers. Let's determine if this statement is correct or not.
Recall the percent proportion. a/b=p/100 The total b were the total number of people working that night 12. The part a were the number of servers which was 9. Let's find the percent p.
a/b=p/100
9/12=p/100
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Solve for p
9/12(100)=p
9(100)/12=p
3(100)/4=p
3(25)=p
75=p
p= 75
We have found that 75 % of the people working were servers. Therefore, the correct option is I.