YOUTUBE VIDEO
PERCENTAGE RATE & BASE
P = R * B
R = P : B
B = P : R
20 is 50% of what number?
P*
[is]
R:
[%]
B:
[of]
20 is 50% of what number?
B = P : R
B = 20 : .5
B = 40
A train traveled 300 kilometers at 120 kph. How long did it travel?
T = D : S
T = 300 : 120
T = 2.5
20 is 50% of what number?
20:B = 50:100
20*100 = B*50
2000 = B*50
2000:50 = [40]
PERCENT OF INCREASE
Part = amount of increase
Base= original amount
The number of students learning Torah increased from 250 to 300 students. What is the percent of increase?
a:b = c:d is ad = bc
R = P : B
50:250 = c:100
is
50*100 = 250*c
5000:250 = c
C = 20%
PERCENT OF DECREASE
aka PERCENT OF DISCOUNT
-follows the same exact formula as PERCENT OF INCREASE
A dozen roses sale for $24. What is the price per unit?
R = P : B
R = $24 : 12
Unit price is $2