Geology Reference
In-Depth Information
38
I. Introduction to Geology
4. Consult Appendix I to determine the value and name for
8.
Complete the sentence. The number of significant figures
the following prefixes in the International System of Units.
in a number is an indication of the
; the more sig-
nificant figures, the more
is the value.
Value
Name
PART B. BASIC CALCULATIONS
AND CONVERSIONS
tera
10
1
2
a.
T
Calculations
Percentage. This calculation determines some part of
a given amount or quantity. The simplest example for
most of us is our score on a test consisting of 100
questions. If we got 70 questions correct we would
have 70 out of 100 or 70% correct. We obtain this by
taking the 70/100 amount and multiplying it by 100%
as follows:
b. G
c. M
d.
k
e.
c
70
— X
100% = 70%.
f. m
g.
n
In this example we have taken some fraction (70/100)
of the 100%. If the total of the points on the test were
106 and the score were the same (70 correct), we would
calculate the percentage score by
h. n
70
— X
100% = 66%.
106
5.
Complete the blanks in the columns to provide the name
and equivalent values in meters.
If we were told we got 20 questions wrong of 106, how
would we calculate our percentage score? Subtract the
20 from the 106 = 86. Then divide 86 by the total num-
ber of questions and multiply by 100% as below:
Full Name
in Meters
a.
1 cm
=
1 centimeter
= 0.01 meter
= 5.5
X
10~
2
meters
b. 5.5 cm =
106 — 20=86 (i.e.,total questions—wrong answers
= correct answers)
c. 5.5 km =
86
— X
100% = 81%
106
d. 1 mm =
6.
Write in long form and scientific notation the equivalent of
4.7 Gyr.
The key here is knowing the quantity for which you
want to determine the percent.
7.
Give the significant figures for the following:
Often we want to know percentage change in some-
thing over a period of time. For example, if the ozone
level in the stratosphere over Antarctica in October
averaged 200 in 1988 and 180 in 1989, what would the
percentage change have been from one year to the next?
We need to compare the change with the original
amount. The change was a decrease of 20; that is
(200 - 180 = 20). The original amount was 200.
Therefore the percentage change is:
a.
2.2
X
10
2
b.
1500
c.
0.028 or 2.8 x 10~
2
20
— X
100% = 10%
d.
0.0440
e.
125.00
