Term
In a survey of 200 people, 90 of whom were female, it was found that 60 people were unemployed, including 20 males.
(a) Using this information, complete the following table.
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Males
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Females
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Totals
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Unemployed
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Employed
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Totals
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200
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(b) If a person is selected at random from this group of 200, find the probability that this person is
(i) an unemployed female;
(ii) a male, given that the person is employed. |
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Definition
(a)
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Males
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Females
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Totals
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Unemployed
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20
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40
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60
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Employed
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90
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50
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140
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Totals
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110
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90
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200
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(b), (i) P(unemployed Female) = 40/200 = 1/5
(ii) P(Male I Employed Person) = 90/140 = 9/14 |
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Term
The heights of certain flowers follow a normal distribution. It is known that 20% of these flowers have a height less than 3 cm and 10% have a height greater than 8 cm.
Find the value of the mean and the standard deviation. |
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Definition
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Term
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Definition
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Term
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Definition
| The probability of a certain event occuring n number of times. |
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Term
The heights of certain flowers follow a normal distribution. It is known that 20% of these flowers have a height less than 3 cm and 10% have a height greater than 8 cm.
Find the value of the mean and the standard deviation |
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Definition
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Term
| What are incluesive and excluesive events? |
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Definition
Exclusive events:
[image]
Incluesive events:
[image] |
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Term
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Definition
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Term
A large box contains a mixture of 3 different types of bolts, in equal numbers. Another box contains nuts for the bolts. Each nut only fits a bolt of the same type.
A nut and a bolt are chosen at random, and checked to see if they mach. (i.e. are of the same type). The process is repeated 12 times.
Find the probability that more than 4 matches are obtained. |
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Definition
X~B(12 1/3)
1-P((x=3) (x=2) (x=1))
P(4 matches) = 0.368 (Approximately) |
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Term
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Definition
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Term
| In the context of probability, define Combinations (what are they used for?) |
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Definition
Combinations are used for calculating the total outcome of dependent events.
[image] |
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Definition
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Definition
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Definition
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Definition
(a)
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y
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0
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1
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2
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3
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4
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P(X=y)
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(4/9 x 3/8 x 2/7 x 1/6)
= 1/126
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(4 nCr 1)(5/9 x 4/8 x 3/7 x 2/6)
= 10/63
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(4 nCr 2)(5/9 x 4/8 x 4/7 x 3/6)
= 10/21
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(4 nCr 3)(5/9 x 4/8 x 3/7 x 4/6)
= 20/63
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(5/9 x 4/8 x 3/7 x 2/6)
= 5/126
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(b)
P(1 or 2 or 3 or 4 women)
= 1 - P (no women)
= 1/126 |
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Definition
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Definition
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