1.Find the percent of decrease. from $25 to $20;
from $65 to $50; from $80 to $45; from $15 to $12;
from $150 to $130; from $12,000 to $8,500
2.Find the discount rate. a $30 book on sale for $20;
a $25,000 automobile on sale for $17,500
3.Express as percents: 6, 6.5, 0.65, 0.065, 4, 4.5 0.045,
9, 9.5, 0.95, 0.095, 8.5, 0.85, 0.085
4.Over 5 weeks the recorded rainfall was: 1 in., 2 in.,
2 in., 3 in., 1 in., 2 in. What is the range?
5.Using the weekly rainfall data above, what is
the mode?
6.Using the same data, what is the average rainfall?- Using the same data, what is the median rainfall?
8. Edna wants a radio that costs $90. If she has $75,
how much more money does she need?
9. The following are spelling scores: 80, 89, 81, 80, 70.
What is the mean? What is the median? - Of the scores above, which is the mode?
- What is the range for this set of data? 90, 89, 89, 80, 70
- Solve each proportion: ; ; ;
; - Find the number: 4 12 % of x; 10 5% of x;
150 20% of x; 200 15% of x; 75 20% of x - Multiply by 1000: 23, 2.3, 0.23, 0.023, 125, 12.5, 1.25,
0.125, 255, 25.5, 2.55, 0.255
1(^21)
2
80
100
n
48
n
20
n
1
1
n
6
5
60
n
12
30
35
7
7
42
1
2
1
4
SET 17...........................................................................................................
1.Find 40% of: $10, $5, $50, 35, 75, 90, 400, $1.75, $1.50,
$600, $2, 120, 55, 80, 600
2.The following are math scores: 90, 81, 81, 80, 75.
What is the mean? What is the median?
3.Of the scores above, which is the mode?
4.What is the range for the same set of data?
90, 81, 81, 80, 75.
5.One angle in a right triangle measures 40. Find the
measure of the third angle.
6.Identify the complementary or supplementary angle
pairs. 65 , 25 ; 110 , 70 ; 35 , 55 ; 95 , 85
- Name the measure of the supplement of each angle:
40
, 100 , 35 , 60 , 5 , 45 , 120 , 110
8. What fractional part of an hour is: 20 min; 40 min;
10 min; 5 min; 15 min, 12 min?
9. 30% of Jon’s day is spent in bed. How long is that? - To travel 15 miles in 20 minutes, how many miles
per hour must you be going? - A tax collector is paid $60 commission for collecting
$1500. Find the rate of commission. - Find the third angle of a triangle if two angles are:
90
and 60 ; 82 and 64 ; 75 and 58 - The opposite angles of a parallelogram measure
100
each. Name the measure of the other angles? - Express in scientific notation: 13,000; 2700; 450,000;
6,000,000; 108,000; 9,810,000.
SET 18..........................................................................................................
1.Find the number: 80% of n100; 25% of n2000;
33 % of n20; 60% of n$3600; 5% of n 75
2.To the nearest penny find 5% of: 60¢, 80¢, 70¢, 50¢
3.Find: 15% of 30; 75% of 150; 20% of 60
4.What is: 80% of 200; 75% of 48; 60% of 60;
90% of 90; 30% of 60; 200% of 80; 60% of 30?
5.Name the kind of triangle in which all angles are
less than 90°.
6.Name the kind of triangle that has three
congruent sides.- Right triangles have two acute angles. What kind of
angle is the third angle? - Into what two shapes does a diagonal divide a
rectangle? - The measure of two of the three angles of a triangle
are given. Name the measure of the remaining
angle. 90 , 45 ; 105 , 20 ; 70 , 75 ; 60 , 50 ; 100 , 30 - Multiply by 3: 6, 6 , 5, 5 , 2, 2 , 7, 7 , 4, 4 , 9, 9 ,
10, 10^34
2
32
31
31
32
31
31
3SET 19..........................................................................................................
1.Find the number: 50% of n500; 20% of n1000;
40% of n100; 75% of n$750; 10% of n 50
2.To the nearest dollar find 15% of: $50, $90, $120
3.From 1000 take: 10^1 , 10^2 , 10^3 , 10^0 , 2^2 , 3^2 , 5^2
4.Take 10^3 from: 2000, 1000, 3500, 64,000, 10,000
5.Tell the range of possible measurements for each
degree of precision. nearest cm: 3 cm; nearest tenth
of a cm: 5.7 cm; nearest in.: 4 in.; nearest tenth of a
cm: 8.1 cm; nearest half in.: 6.7 in.- Arrange in order from least to most precise.
4.01 cm, 4.1 cm, 4.014 cm, 4 cm;
15.4 g, 15.054 g, 15 g, 15.04 g - What percent of 360 is: 60 , 90 , 120 , 180 , 30 , 40 ,
160
, 200 , 225 , 280 , 300? - What percent of 360 is: 20 , 50 , 70 , 85 , 95 , 110 ,
155
, 200 , 280 , 310 , 320? - Find the circumference of a circle when the
diameter is: 14 cm, 2.1 m, 28 in., 3.5 m, 70 mm, 1.4 m
SET 20.........................................................................................................
Mental Math 421