P.O.D. #1

Convert ⅝ to a decimal and to a percent.

Decimal: 5 ÷ 8 = 0.625

Percent: 0.625 100% = 62.5%

Determine the value of t.

1419

= t95

14 95 = 19 t 1330 = 19t ÷19 ÷19

70 = t

basic advanced

Probability of Simple Events

The probability of an event is a ratio that compares the number of favorable outcomes to the number of possible outcomes.

0 1½ ¾¼

Impossible UnlikelyAs likely to

happen as not Likely Certain

0 0.25 0.5 0.75 1

0% 25% 50% 75% 100%

Fraction:

Decimal:

Percent:

The probability of a chance event is a number between 0 and 1.

P(event) = Number of favorable outcomesNumber of possible outcomesExample:You roll a number cube. What is the probability of rolling an odd number?

P(odd) =36 =

12

Example:

The probability that you draw a short straw out of a group of 40 straws is 3/20. How many straws are short?

320

x40=

3 40 = 20 x 120 = 20x ÷20 ÷20

6 = x

Set up a proportion:

Cross multiply:

Solve for variable:

Six out of the 40 straws are short.

Complementary events are two events in which either one or the other must happen, but they cannot happen at the same time.

Example:

The probability of not rolling a 4 and the probability of rolling a 4 are complementary.

P(4) + P(not 4) = ?

16

+ 56

= 1

The sum of the probability of an event and its complement is 1 or 100%.

Whiteboard:

You randomly choose one hat from 3 green hats, 4 black hats, and 2 white hats. What is the probability that you will choose a green hat?

P(green) =39 =

13

Decimal: 0.33

Percent: 33%

Whiteboard:

Miss Bush surveyed her class and discovered that 70% of her students own a cellphone. Find the probability that a student does not own a cellphone.

P(phone) + P(not phone) = 100%

70% + P(not phone) = 100%

-70% -70%

P(not phone) = 30%

Whiteboard:

Miss Bush surveyed her class and discovered that 70% of her students own a cellphone. If there are 20 students in her class, how many own cellphones?

70100

x20=

70 20 = 100 x 1400 = 100x ÷100 ÷100

14 = x