Chap 17 - Managing money

Question 1

formula for simple interest

Answer 1

P = principle
R = rate from % in DECIMALS
t = time
simple interest = PRT
* only simple interest, not total money*

Question 2

formula for compound interest

Answer 2

P = principle
R = rate from % in DECIMALS
t = time
A = total amount
P (1 +/ - R)^ t = A
-appreciation/ growth = ( + )
-depreciation/ decay = ( - )
*total money including compound interest

Question 3

note: in a graph, time always x axis

Question 3

note:
population/ diseases growth = compound
p.a = per annum (per year) = compound
flat rate = simple

Question 4

define gross income

Answer 4

money before deduction

Question 5

formula when writing/ solving compound interest

Answer 5

• P ( 1+ r/ 100)^ t = A
  r/ 100 because r has to be in decimal, not %
• 1 + r/ 100 = t^√A/P

Question 6

define net income

Answer 6

money after deduction

Question 7

how to find tax from taxable income (gross income) bracket

Answer 7

eg. $23 760 (x) + 25% (%) of the amount above $132 000 (y)
x + % of the amount over y
z = gross income
formula:
x + (% x [z - y]) = tax needed to pay

Question 8

formula for % profit/ loss

Answer 8

profit/ loss
—————— X 100%
cost price

Question 8

formula to find original price after mark up/ down

Answer 8

y= original price
y X 1 - mark up/ down in decimals = new price
y = new price/ 1 - mark up/ down in decimals
eg. 18.24 discounted price after 12% mark down
y x 0.88 = 18.24
y = 18.24/ 0.88
y = 20.73

Question 9

what is over time: time & a half, & double time

Answer 9

time & a half - principle x 1.5 for every t
double time - principle x 2 for every t