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Find the indicated conditional probability

using the following two-way table:
Grade
Drive to school
Take the bus
Walk
Sophomore
2
25
3
Junior
13
20
2
Senior
25
5
5
P( Drive to school | Senior ) = [?]
Round to the nearest hundredth.

Find the indicated conditional probability using the following two-way table: Grade-example-1
User VMAtm
by
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2 Answers

2 votes

Answer:

.71

Explanation:

User Simon Judd
by
4.7k points
7 votes

Given:

The two way table.

To find:

The conditional probability of P(Drive to school | Senior).

Solution:

The conditional probability is defined as:


P(A|B)=(P(A\cap B))/(P(B))

Using this formula, we get


P(\text{Drive to school }|\text{ Senior})=\frac{P(\text{Drive to school and senior})}{P(\text{Senior})} ...(i)

From the given two way table, we get

Drive to school and senior = 25

Senior = 25+5+5

= 35

Total = 2+25+3+13+20+2+25+5+5

= 100

Now,


P(\text{Drive to school and senior})=(25)/(100)


P(\text{Senior})=(35)/(100)

Substituting these values in (i), we get


P(\text{Drive to school }|\text{ Senior})=((25)/(100))/((35)/(100))


P(\text{Drive to school }|\text{ Senior})=(25)/(35)


P(\text{Drive to school }|\text{ Senior})=0.7142857


P(\text{Drive to school }|\text{ Senior})\approx 0.71

Therefore, the required conditional probability is 0.71.

User Anjali A
by
5.3k points