Download TENTATIVE LABORATORY SCHEDULE (Molecular - Bio-Link

1
Quiz 3 Answer Key
(Chapter 5: Using Equations to Describe a Relationship and Chapter 6:
Ratios and Proportions)
1. The sum of four times a number and 5 is 23. Write the equation that
describes the situation. Find the number.
4X + 5 = 23
4X = 18
X = 4.5
2. The sum of five times a number and seven is equal to the sum of three
times that same number and 15. Write the equation that describes the
situation, and find that number.
5X + 7 = 3X + 15
2X = 8
X=4
3. Solve for ? by cross multiplying and dividing. Show your work. Include
units!!!
a. ? = 1
54 3
? = 18
c. _____?
=
152 inches2
b. ? =
4 cm
15 mL
45 mL
? = 1.333 cm
5 pounds
40 inches2
? = 19 pounds
4.. In the following problems:
Set up the proportion equation (with the proper units)
Cross multiply and divide to solve for the unknown.
a. If it requires 80 minutes to drive to Milwaukee, how long will a student
who lives in Milwaukee spend each day commuting to and from school in
Madison?
80 min = X
X = 160 min
1 trip 2 trips
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b. If a recipe requires 1/4 teaspoon of baking powder to make one batch,
how much baking powder is required to make two batches?
1/4 tsp = X
X = 1/2 tsp
1 batch 2 batches
c. If there are about 2 X 102 blood cells in a 1.0 X 10-2 mL sample, about
how many blood cells would be in 2.0 mL of this blood?
2 X 102 blood cells = X
X = 40,000 blood cells
1.0 X 10--2 mL
2 mL
d. 15 grams NaCl are required to make 1 liter of a salt solution. How much
NaCl is needed to make 400 mL of this solution?
15 g NaCl = X
X = 6 g NaCl
1L
0.4 L
e. A particular solution contains 150 mg/mL of enzyme. How much
enzyme is needed to make 104 L of solution?
150 mg enzyme = X
X = 1500 mg enzyme
1 mL solution 10 mL solution
f. 1 mole of carbon has a mass of 12 grams. What is the mass of 0.036
moles of carbon?
12 g C = X
X = 0.43 g carbon
1 mole 0.036 moles
g. 1 mole of table salt (NaCl) has a mass of 58.5 g. What is the mass of 2.5
moles of table salt?
58.5 g NaCl = X
X = 146.25 g NaCl
1 mole
2.5 moles