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Consider the probability distribution shown here

  1. Calculate μ,σ2²¹²Ô»åσ.
  2. Graph p(x). Locateμ,μ−2σ²¹²Ô»åμ+2σ on the graph.
  3. What is the probability that x is in the interval μ+2σ ?

Short Answer

Expert verified

a.μ=−2.61σ2=10.1957σ=3.193071

b.

c. 179%

Step by step solution

01

(a) Calculation of  μ

The calculation μ is shown below:

μ=³§³Ü³¾³¾²¹³Ù¾±´Ç²Ô o´Ú [³Õ²¹±ô³Ü±ð o´Ú x×P(x)]=(−4)0.2+(−3)0.7+(−2)0.1+(−1)0.15+(0)0.3+(1)0.18+(2)0.1+(3)0.06+(4)0.02=−2.61

02

Calculation of σ2and σ

The calculation σ2²¹²Ô»åσis shown below:

σ2=³§³Ü³¾³¾²¹³Ù¾±´Ç²Ô o´Ú [(³Õ²¹±ô³Ü±ð o´Ú x−μ)×P(x)]=(−4−2.61)0.2+(−3−2.61)0.7+(−2−2.61)0.1+(−1−2.61)0.15+(0−2.61)0.3+(1−2.61)0.18+(2−2.61)0.1+(3−2.61)0.06+(4−2.61)0.02=10.1957

σ=10.1957=3.193071

Therefore the μ,σ2²¹²Ô»åσ are -2.61, 10.1957 and 3.193071.

03

(b) Calculation of μ−2σ and μ+2σ

The calculation μ−2σ²¹²Ô»åμ+2σ is shown below:

μ−2σ=−2.61−2×3.193071=−8.99614μ+2σ=−2.61+2×3.193071=3.78

Therefore, the values μ,μ−2σ²¹²Ô»åμ+2σ are -2.61, -8.99614 and 3.78, respectively.

04

Graphical representation of p(x),μ, μ−2σ and μ+2σ

In the graphical representation shown above, the respective probabilities are given, and in the horizontal axis, the respective values of x are given. Within the horizontal axis, the respective variablesμ,μ−2σ²¹²Ô»åμ+2σ are labelled.

05

(c) Definition of Chebychev’s rule

Chebycheb’s rule assumes that there are two standard deviations in the model. The rule says the maximum number of the values or observations must lie within the given standard deviations.

06

Calculation of the probability

As the value μ+2σis 3.78, the summation of the probabilities from -4 to 3 will be the answer as shown below:

³§³Ü³¾³¾²¹³Ù¾±´Ç²Ô o´Ú t³ó±ð p°ù´Ç²ú²¹²ú¾±±ô¾±³Ù¾±±ð²õ=0.2+0.7+0.10+0.15+.30+0.18+0.10+0.06=1.79

³§³Ü³¾³¾²¹³Ù¾±´Ç²Ô o´Ú t³ó±ð p°ù´Ç²ú²¹²ú¾±±ô¾±³Ù¾±±ð²õ=0.2+0.7+0.10+0.15+.30+0.18+0.10+0.06=1.79

Multiplying 1.79 by 100, it becomes 179%, which means 179% of the probability distribution lies within the given distributions.

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