Question
Fill in the blanks in the following table:
  P(A) P(B) $\text{P}({\text{A}}\cap{\text{B}})$ $\text{P}({\text{A}}\cup{\text{B}})$
(i) $\frac{1}{3}$ $\frac{1}{5}$ $\frac{1}{15}$ .......
(ii) 0.35 .... 0.25 0.6
(iii) 0.5 0.35 .... 0.7

Answer

  1. Given,
P(A) $=\frac{1}{3},\ \text{P}(\text{A}\cap\text{B})=\frac{1}{15}$

P(B) $=\frac{1}{5},\ \text{P}(\text{A}\cup\text{B})=\ .......$

$\because\text{P}(\text{A}\cup\text{B})=\text{P}(\text{A})+\text{P}(\text{B})-\text{P}(\text{A}\cap\text{B})$

$=\frac{1}{3}+\frac{1}{5}-\frac{1}{15}$

$=\frac{5+3-1}{15}$

$=\frac{8-1}{15}=\frac{7}{15}$

$\because\text{P}(\text{A}\cup\text{B})=\frac{7}{15}$
  1. Given,
P(A) = 0.35, P(B) = ....

$\text{P}(\text{A}\cap\text{B})=0.25,\ \text{P}(\text{A}\cup\text{B})=0.6$

$\because\text{P}(\text{A}\cup\text{B})=\text{P}(\text{A})+\text{P}(\text{B})-\text{P}(\text{A}\cap\text{B})$

$0.6=0.35+\text{P}(\text{B})-0.25$

$0.6=0.10+\text{P}(\text{B})$

$\text{P}(\text{B})=0.6-0.1$

$\text{P}(\text{B})=0.5$
  1. Given
P(A) = 0.5, P(B) = 0.35

$\text{P}(\text{A}\cap\text{B})=\ ...,\ \text{P}(\text{A}\cup\text{B})=0.7$

$\because\text{P}(\text{A}\cup\text{B})=\text{P}(\text{A})+\text{P}(\text{B})-\text{P}(\text{A}\cap\text{B})$

$0.7=0.5+0.35-\text{P}(\text{A}\cap\text{B})$

$0.7=0.85-\text{P}(\text{A}\cap\text{B})$

$\text{P}(\text{A}\cap\text{B})=0.85-0.7$

$\text{P}(\text{A}\cap\text{B})=0.15$

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