# ( ) Math 141 Week in Review Week 3 Problem Set Answers

```Math 141 Week in Review
1.
y=
2
4
x!
3
7
2.
n=
8
3
3.
A. \$6
B. P ( x ) = 4 x !1500
C. 375 keychains
D. \$2250
4.
1
A. Demand: p = ! x + 75
8
1
Supply: p = x + 15
4
B. (160, 55); 160 sleeping bags at \$55 each
5.
A. y = 71.39x – 201
B. 1227 stores
C. 2012
D. r ≈ 0.9665. Since |r| is very close to 1, the line models the data very well.
6.
A. Yes; No Solution
B. No; !9R2 + R1 &quot; R1
C. Yes; Exactly 1 solution
D. No; !R2 + R3 &quot; R3
E. No; 13 R2 ! R2
F. Yes; Infinitely many solutions
7.
1
4
R1 ! R1
&quot;1 2
\$
#!3 !5
8 %
'
!18&amp;
3R1 + R2 ! R2
!1 2
#
&quot;0 1
8\$
&amp;
6%
!2R2 + R1 &quot; R1
&quot;1 0
\$
#0 1
!4%
'
6&amp;
The solution is (–4, 6)
8.
x = the number of Dr Peppers
y = the number of coffees
68x + 230y = 1830
250x + 130y = 3150
Jill drank 10 Dr. Peppers and 5 coffees.
9.
A. No Solution
B. Infinitely many solutions; (!t + 3,t !1,t )
10.
a = 8, b = –4, c = 21, d =
11.
B = [5 3 6] ; BA = [129 133]
John will spend \$129 if he orders from Papa John’s and \$133 if he orders from
Pizza Hut.
12.
A.
B.
C.
D.
E.
13.
A. x = the number of Southwest flights
y = the number of Delta flights
z = the number of American flights
1
2
Possible
Not Possible
Possible
Possible
Not Possible
135x + 160y + 148z = 88,683
x = 3y
z = 12 ( x + y )
&quot;135 160 148%&quot; x% &quot;88683%
\$
'\$ ' \$
'
!3
0 '\$ y' = \$ 0 '
B. \$ 1
\$# ! 1 ! 1
1 '&amp;\$# z '&amp; \$# 0 '&amp;
2
2
&quot;309%
\$ '
C. X = A!1B = \$103' ;
\$#206'&amp;
There were 309 Southwest flights, 103 Delta flights, and 206 American flights.
14.
!0.2 0.3 0.2\$
#
&amp;
A. A = #0.1 0.4 0.1&amp;
#&quot;0.1 0.3 0.3&amp;%
!1700\$
#
&amp;
B. X = #1200&amp;; 1700 units of agricultural products, 1200 units of transportation,
#&quot;1050&amp;%
and 1050 units of service.
&quot;910%
\$ '
C. AX = X ! D = \$755' ; 910 units of agricultural products, 755 units of
\$#845'&amp;
transportation, and 845 units of service.
```