1­3 Day 2 Solving Equations word problems 2010
August 27, 2010
1­3 Day 2 Solving Equations
Objective:
Solve problems by writing equations.
Jun 25­7:38 PM
1
1­3 Day 2 Solving Equations word problems 2010
August 27, 2010
Check Skills You'll Need
Solve each equation:
1. 43 ­ 3d = d + 9
2. 6(t ­ 2) = 2(9t ­ 4)
3. 6(n ­ 4) = 3n
4. 12 ­ 3(2w + 1) = 7w ­3(7 + w)
5. 7(a + 1) ­ 3a = 5 + 4(2a ­ 1)
Jun 25­7:46 PM
2
1­3 Day 2 Solving Equations word problems 2010
August 27, 2010
1. A dog kennel owner has 100 ft. of fencing to enclose a rectangular dog run. She wants it to be 5 times as long as it is wide. Find the dimensions of the dog run.
Step 1: Draw a diagram.
Step 2: Define your variables
Let x = the width
Let 5x = the length
Step 3: Write an equation and solve.
x + 5x + x + 5x = 100
12x = 100
x = 25/3
x = 8 1/3
Therefore 5x = 5(8 1/3) = 41 2/3
Width = 8 1/3 ft.
Length = 41 2/3 ft.
Jun 25­7:53 PM
3
1­3 Day 2 Solving Equations word problems 2010
August 27, 2010
2. A rectangle is twice as long as it is wide. Its perimeter is 48 cm. Find its dimensions.
Aug 26­12:21 PM
4
1­3 Day 2 Solving Equations word problems 2010
August 27, 2010
3. The lengths of the sides of a triangle are in the ratio 3:4:5. The perimeter of the triangle is 18 in. Find the lengths of the sides.
Step 1: Draw a diagram.
Step 2: Define your
Let 3x =
Let 4x =
Let 5x =
variables
length of shortest side
length of the second side
length of the third side
Step 3: Write an equation and solve.
3x + 4x + 5x = 18
12x = 18
x = 3/2
x = 1.5
Therefore 3x = 3(1.5) = 4.5
4x = 4(1.5) = 6
5x = 5(1.5) = 7.5
Jun 25­8:11 PM
5
1­3 Day 2 Solving Equations word problems 2010
August 27, 2010
Aug 25­10:43 AM
6
1­3 Day 2 Solving Equations word problems 2010
August 27, 2010
4. Two trains leave Denver at the same time going in opposite directions. The northbound train is going 51 mph and the southbound train is traveling 62 mph. How far apart are the trains after 7.4 hours of traveling?
Aug 26­12:23 PM
7
1­3 Day 2 Solving Equations word problems 2010
August 27, 2010
5. Two trains leave Union Station in Denver going South down the same tracks by accident? The first train leaves going 60 mph. The second train leaves 30 minutes later going 63 mph. How long before the second train runs into the first train?
Aug 26­12:22 PM
8
1­3 Day 2 Solving Equations word problems 2010
August 27, 2010
6. Radar detected an unidentified plane 5000 miles away, approaching at 700 mi/hr. Fifteen minutes later an interceptor plane was dispatched, traveling at 800 mi/hr. How long did the interceptor take to reach the approaching plane?
Step 1: Understand the question.
distance for interceptor + distance for approaching plane = 5000 mi.
Step 2: Define your variables
t = time in hours for interceptor
t + 0.25 = time in hours for the approaching plane
Step 3: Write an equation and solve.
800t + 700(t + 0.25) = 5000
800t + 700t + 175 = 5000
1500t + 175 = 5000
1500t = 4825
t = 3.217 or 3 hr 13 min
Jun 25­8:36 PM
9
1­3 Day 2 Solving Equations word problems 2010
August 27, 2010
HOMEWORK
1.1 ­ 1.3 Review
Hmwk Check on Friday!!
Quiz on Monday!!
Jun 25­8:44 PM
10