the enm 503 pretest an exercise in frustration let’s see now. i remember that a log is associated...
TRANSCRIPT
The ENM 503 PretestAn exercise in frustration
Let’s see now. I remember that a log is
associated with the lumber industry and a radical favors extreme
change?
The ENM 503 Pre-Test Results
Statistics: Mean and median – 60 percent Average number missed: 16 out of
40 Median number missed: 16 Minimum number missed: 9 Maximum number missed: 24 Standard deviation: 12.5%
I really enjoyed
that pretest.
Me too! This is going to be one of
my favorite classes.
Engineering management students enjoy reminiscing about today’s class.
Problem 2
If an automobile averaged 40 miles per (mph) for 45 minutes and 50 mph for 1.5 hours, how far did it travel?
40 x 45/60 + 50 x 1.5 = 30 + 75 = 105 miles
Problem 3
Subtract (-2a + 7x – 5c2) from (-2x + 8a + c2)
(-2x + 8a + c2) - (-2a + 7x – 5c2) - = -2x + 8a + c2 +2a - 7x + 5c2
= -9x + 10a +6c2
Problem 6
Multiply: (-3st2) (2s2t3) (-2s2t2) = ?
(-3st2) (2s2t3) (-2s2t2) =12s5 t7
We know how to multiply.
Problem 7
Find the values for x for which -3x + 2 < 0.
-3x < -2
X > 2/3Read me the story again about
changing the direction of an inequality when dividing by a
negative number.
Problem 8
Express in simplest terms: 5 2
6 5
21
3
x z
x z
5 2 3
5 2 6 56 5
21 77
3
x z zx z x z
x z x
Problem 11
Solve for y: y – (1/3) y + 1 = 3 – (2/3) y (2/3)y + 1 = 3 – (2/3)y (4/3)y = 2 Y = 2(3/4) = 6/4 = 1.5
Problem 12
Solve for w and z : w – 2z – 3 = 0
2w + 2z + 6 = 0
3W + 3 = 0
W = -1, Z = -2You nailed this
one Chuck.
Problem 13 An equilateral triangle is one whose sides are
all the same length. If the perimeter of an equilateral triangle is 36 inches, what is its height?
Side (hypotenuse) = 12; 144 – 36 = 108
108 6 3 10.4in
Problem 18
A man has a rope 180 feet long that he wishes to cut into three parts in the ratio of 2:3:4. How long in feet will each piece of the rope be?
2x + 3x + 4x = 1809x = 180 x = 20therefore ratio is 40:60:80
Problem 19
If y varies directly with x (i.e. y is directly proportional to x), and y = 8 when x = 4, what is the value of y when x = 6?
y = kx8 = k4 k = 2
y = 2x = 2(6) =12
Problem 22 A man has a car with a 6 gallon radiator filled with a
solution containing 10 percent coolant. He drains off a certain amount and replaces it with a solution that contains 70 percent coolant. How much was drained off if the solution then contained 20 percent coolant?
Let x = gallons drained.70x + .10(6-x) = .20(6).7x - .1x = 1.2 - .6 = .6 x = 1 gallon
Problem 25
(reduce to simplest terms)
2 2
3 3 6 6?
a b b a
x y x y
2 2 2 2
3 3 6 6 3 3
6 6
3 1
6( ) 2
a b b a a b x y
x y x y x y b a
a b x y
x y x y b a x y
I like things in simplest terms.
Problem 27 Two airfields A and B are 400 miles apart and B is due east of
A. A plane flew from A to B in 2 hours and then returned to A in 2.5 hours. The wind blew with a constant velocity from the west during the entire trip, find the speed of the plane in still air and the speed of the wind.
Let x = speed of the airplane and y = speed of the wind recall that distance/ rate = time
400200
2400
1605 / 2
2 360
180mph; 200 180 20mph
x y
x y
x
x y
Problem 28 Expand: (x – 2y)3 = ? (x-2y)(x-2y)(x-2y) = (x-2y)[x2 – 4xy + 4y2] = x3 – 4x2y + 4xy2 -2x2y + 8xy2 – 8y3
= x3 - 6x2y + 12xy2 – 8y3
Press the button
Problem 29
The amount of money available at simple interest is equal to the principle plus the product of the principle, the rate, and the time. Find the time required for a principle of $300 to accumulate to $336 at 4 percent per year.
t = amount of time (years) required300 + 300 (.04) t = 33612t = 36 t = 3 years
Problem 31
The perimeter of a rectangle is 20 inches and one side is 4 inches. What is its area?
Perimeter = 2 length + 2 width = 202 length + 2(4) = 20length = 6
Area = length x width = 6 x 4 = 24 sq. in.
Problem 32 Perform the indicated operation and simplify:
2 2
2 2
1
2 1 2
x x x
x x x x
2 2
22 2
2 2
1 1 11
2 1 2 2 11
2 1 11
1 2 1 2
2 1 1 2
1 2 1 2
x x x xx x x
x x x x x xx
x x x xx x
x x x x
x x x x
x x x x
Problem 33
Rationalize the denominator (eliminate the radical from the denominator):
5
10 3
5 10 35 10 3
5 10 310 910 3 10 3
It always bothers me to see a radical
in the denominator.
Problem 34
Factor completely: 2x4 y – 32y = ? 2y (x4 – 16) = 2y (x2 + 4) (x2 - 4) 2y (x2 + 4) (x - 2) (x+2)
I just ran out of time.
Problem 35
Remove parentheses and simplify 2/31/ 2
3
3 8
2 27
x x
y y
2/3 1/31/ 2 1/3 4 /3
3 2 6 2 2 3
3 8 3 64 3 4 2
2 27 2 27 2 3 3
x x x x x x x
y y y y y y y
Problem 36
Solve for x: log10 x3 – 2 log10
x = 2
3 log10 x – 2 log10 x = 2
log10 x = 2 x = 102 = 100 My head
hurts.
Problem 38
The following system of equations has how many solutions?
2x + 3y = 10
4x + 6y = 7 Why, I can’t find any solution to
these equations.