Percent

Question 1

Increase p by x percent

Answer 1

p(1+(x/100))

eg. p is increased by 90%=p(1.9)

Question 2

Decrease p by x percent

Answer 2

p(1-(x/100))

eg. p is decreased by 40%=p(1.6)

Question 3

p value is changed by x, y and z percents; mindset of setting up the equation?

Answer 3

String all changes together and calculate the end result only after doing so

eg. decrease 100 by 90%, increase it by 10% and decrease by 50% instead of calculating 0.1 of 100 and then 1.1 of that and then 0.5 of that, do the following:
100(0.1)(1.1)(0.5)=100(0.055)=something

Question 4

Compound Interest formula

Answer 4

A=P((1+(r/n))^nt), where
A=final amount
P=principle amount
r=rate
t=time (usually annually)
n=how many times it is compounded per unit time (eg. semiannually means n=2 if t=1 year)

Question 5

The relation between n and a in the compound interest formula

Answer 5

as n increases, A does exponentially

Question 6

Simple Interest Formula

Answer 6

A=P(1+rt), were
A=final amount
P=principle amount
r=rate
t=time

Question 7

Percent change formula

Answer 7

((new value-old value)/old value)*100%

Question 8

if y decreases 20 percent from year k to year x. How many y’s were present in year k?

Answer 8

0.8k=x because year x is 80% of year k

k=x/0.8

Question 9

While revision, check the percent change in a hypothetical variable

Answer 9

Assign a random # (100 mayhaps) to the variable