Lesson 2 - Practice Problems

Lesson 2 - Practice Problems#

  1. Convert the following numbers to engineering notation:

46500000 V

0.00000983 A

792000000000 Ω

6150 V 0.0019 A

20000000000 Ω

  1. Use the decision matrix below to determine which laptop would be the best choice.

Screen Size

Cost

Laptop A

15

$1000

Laptop B

17

$1200

Decision matrix:

Laptop

—-

Screen Size

—-

—-

Cost

—-

Total

Weight

———–

———–

———–

———–

————

Value

Norm

Weighted

Value

Norm

Weighted

A

B

  1. Determine which house would be the best choice.

Commute Time

Square Footage

Cost

House A

15 min

2000

$220000

House B

5 min

1500

$250000

House C

30 min

3000

$200000

Decision matrix:

House Commute Square Cost Total Time Footage

Weight

          Value       Norm   Weighted   Value       Norm   Weighted   Value      Norm   Weighted

A

B

C

House

—-

Communte time

—-

—-

Square Footage

—-

—-

Cost

—-

Total

Weight

—-

Determined in Class

—-

—-

Determined in Class

—-

—-

Determined in class

Value

Norm

Weighted

Value

Norm

Weighted

Value

Norm

Weighted

A

15

0.333

2000

0.667

$220K

0.909

B

5

1.000

1500

0.500

$250K

0.800

c

30

0.167

3000

1.000

$200K

1.000

  1. You are evaluating three different AC-to-DC converters that all meet your requirements for ripple (how much the supposed DC output actually changes) and cost. Since you want to use these devices for a scientific instrument, you really want to minimize ripple but are limited by a small budget. Use a decision matrix to choose the best one. Assume a weight of 60% for ripple and 40% for cost.

Part

Ripple

Cost

A

30mV

$20

B

35mV

$14

C

45mV

$12

Weight

         Value        Norm     Weighted   Value      Norm     Weighted

A

B

C

  1. Three options are proposed to provide power to a new community. The cost and efficiency for each option are shown below.

Option

Cost

Efficiency

X

$3.2M

99.4%

Y

$3.0M

97.2%

Z

\2.8M

86.0%

(a) If cost and efficiency are considered equally as important, which is the better option?

Option Cost Efficiency Total

Weight

           Value      Norm     Weighted   Value            Norm     Weighted

X

Y

Z

(b) If efficiency is considered 9 times as important as cost, which is the better option?

Option Cost Efficiency Total

Weight

           Value      Norm     Weighted   Value            Norm     Weighted

X

Y

Z

  1. Convert the following in to engineering notation:

(a) 5.45 x 10^-7^ A

(b) 123,400 W

(c) 8.33 x 10^7^ V

(d) 4.3 x 10^10^ bits (b)

(e) 1,497,000 Hz

(f) 76.2 x 10^-4^ m

(g) 2.31 x 10^-5^ m

(h) 1.78 x 10^-14^ W