Math Flashcards
0
Q
World population?
A
7e9.
7 billion
1
Q
Us population?
A
3e8.
300 million
2
Q
1 hectare is how many acres?
A
2.47 acres
3
Q
1 kwh is how many btus?
A
3412.14 btus
4
Q
How do you calculate a percentage?
A
(Part/whole)*100
5
Q
Growth rate?
A
[(crude birth rate + immigration)-(crude death rate +emigration)]
6
Q
Percent change ?
A
(Cbr-cdr)/10
7
Q
Percent change from one period to another?
A
[(original-new)/original]*100
8
Q
Annual rate of change?
A
Percent change from one period to another / number of years
9
Q
Rule of 70?
A
Predicts doubling time.
70/annual growth rate
10
Q
Half life?
A
Amount remaining=(original)(.5)^x
X=time/half life
11
Q
Npp=
A
Gpp-respiration
