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In a county containing a large number of rural homes, 60% of the homes are insured against fire. Four rural homeowners are chosen at random from this county, and x are found to be insured against fire. Find the probability distribution for x.

Sagot :

Answer:

[tex]\begin{array}{cccccc}x & {0} & {1} & {2} & {3} & {4} \ \\ P(x) & {0.0256} & {0.1536} & {0.3456} & {0.3456} & {0.1296} \ \end{array}[/tex]

Step-by-step explanation:

Given

[tex]p = 60\%[/tex]

[tex]n = 4[/tex]

Required

The distribution of x

The above is an illustration of binomial theorem where:

[tex]P(x) = ^nC_x * p^x *(1 - p)^{n-x}[/tex]

This gives:

[tex]P(x) = ^4C_x * (60\%)^x *(1 - 60\%)^{n-x}[/tex]

Express percentage as decimal

[tex]P(x) = ^4C_x * (0.60)^x *(1 - 0.60)^{n-x}[/tex]

[tex]P(x) = ^4C_x * (0.60)^x *(0.40)^{4-x}[/tex]

When x = 0, we have:

[tex]P(x=0) = ^4C_0 * (0.60)^0 *(0.40)^{4-0}[/tex]

[tex]P(x=0) = 1 * 1 *(0.40)^4[/tex]

[tex]P(x=0) = 0.0256[/tex]

When x = 1

[tex]P(x=1) = ^4C_1 * (0.60)^1 *(0.40)^{4-1}[/tex]

[tex]P(x=1) = 4 * (0.60) *(0.40)^3[/tex]

[tex]P(x=1) = 0.1536[/tex]

When x = 2

[tex]P(x=2) = ^4C_2 * (0.60)^2 *(0.40)^{4-2}[/tex]

[tex]P(x=2) = 6 * (0.60)^2 *(0.40)^2[/tex]

[tex]P(x=2) = 0.3456[/tex]

When x = 3

[tex]P(x=3) = ^4C_3 * (0.60)^3 *(0.40)^{4-3}[/tex]

[tex]P(x=3) = 4 * (0.60)^3 *(0.40)[/tex]

[tex]P(x=3) = 0.3456[/tex]

When x = 4

[tex]P(x=4) = ^4C_4 * (0.60)^4 *(0.40)^{4-4}[/tex]

[tex]P(x=4) = 1 * (0.60)^4 *(0.40)^0[/tex]

[tex]P(x=4) = 0.1296[/tex]

So, the probability distribution is:

[tex]\begin{array}{cccccc}x & {0} & {1} & {2} & {3} & {4} \ \\ P(x) & {0.0256} & {0.1536} & {0.3456} & {0.3456} & {0.1296} \ \end{array}[/tex]