For a loaded die, the probabilities of outcomes are given as under:

    \[\mathbf{P}\left( \mathbf{1} \right)\text{ }=\text{ }\mathbf{P}\left( \mathbf{2} \right)\text{ }=\text{ }\mathbf{0}.\mathbf{2},\text{ }\mathbf{P}\left( \mathbf{3} \right)\text{ }=\text{ }\mathbf{P}\left( \mathbf{5} \right)\text{ }=\text{ }\mathbf{P}\left( \mathbf{6} \right)\text{ }=\text{ }\mathbf{0}.\mathbf{1}\text{ }\mathbf{and}\text{ }\mathbf{P}\left( \mathbf{4} \right)\text{ }=\text{ }\mathbf{0}.\mathbf{3}\]

. The die is thrown two times. Let A and B be the events, ‘same number each time’, and ‘a total score is

    \[10\]

or more’, respectively. Determine whether or not A and B are independent.
For a loaded die, the probabilities of outcomes are given as under:

    \[\mathbf{P}\left( \mathbf{1} \right)\text{ }=\text{ }\mathbf{P}\left( \mathbf{2} \right)\text{ }=\text{ }\mathbf{0}.\mathbf{2},\text{ }\mathbf{P}\left( \mathbf{3} \right)\text{ }=\text{ }\mathbf{P}\left( \mathbf{5} \right)\text{ }=\text{ }\mathbf{P}\left( \mathbf{6} \right)\text{ }=\text{ }\mathbf{0}.\mathbf{1}\text{ }\mathbf{and}\text{ }\mathbf{P}\left( \mathbf{4} \right)\text{ }=\text{ }\mathbf{0}.\mathbf{3}\]

. The die is thrown two times. Let A and B be the events, ‘same number each time’, and ‘a total score is

    \[10\]

or more’, respectively. Determine whether or not A and B are independent.

Given that a loaded die is thrown such that

    \[\mathbf{P}\left( \mathbf{1} \right)\text{ }=\text{ }\mathbf{P}\left( \mathbf{2} \right)\text{ }=\text{ }\mathbf{0}.\mathbf{2},\text{ }\mathbf{P}\left( \mathbf{3} \right)\text{ }=\text{ }\mathbf{P}\left( \mathbf{5} \right)\text{ }=\text{ }\mathbf{P}\left( \mathbf{6} \right)\text{ }=\text{ }\mathbf{0}.\mathbf{1}\text{ }\mathbf{and}\text{ }\mathbf{P}\left( \mathbf{4} \right)\text{ }=\text{ }\mathbf{0}.\mathbf{3}\]

and die is thrown two times. Also given that:

A = same number each time and

B = Total score is

    \[10\]

or more.

So, P(A) =

    \[\left[ P\left( 1,\text{ }1 \right)\text{ }+\text{ }P\left( 2,\text{ }2 \right)\text{ }+\text{ }P\left( 3,\text{ }3 \right)\text{ }+\text{ }P\left( 4,\text{ }4 \right)\text{ }+\text{ }P\left( 5,\text{ }5 \right)\text{ }+\text{ }P\left( 6,\text{ }6 \right) \right]\]

=

    \[P\left( 1 \right).P\left( 1 \right)\text{ }+\text{ }P\left( 2 \right).P\left( 2 \right)\text{ }+\text{ }P\left( 3 \right).P\left( 3 \right)\text{ }+\text{ }P\left( 4 \right).P\left( 4 \right)\text{ }+\text{ }P\left( 5 \right).P\left( 5 \right)\text{ }+\text{ }P\left( 6 \right).P\left( 6 \right)\]

=

    \[0.2\text{ }x\text{ }0.2\text{ }+\text{ }0.2\text{ }x\text{ }0.2\text{ }+\text{ }0.1\text{ }x\text{ }0.1\text{ }+\text{ }0.3\text{ }x\text{ }0.3\text{ }+\text{ }0.1\text{ }x\text{ }0.1\text{ }+\text{ }0.1\text{ }x\text{ }0.1\]

=

    \[0.04\text{ }+\text{ }0.04\text{ }+\text{ }0.01\text{ }+\text{ }0.09\text{ }+\text{ }0.01\text{ }+\text{ }0.01\text{ }=\text{ }0.20\]

Now, B =

    \[\left[ \left( 4,\text{ }6 \right),\text{ }\left( 6,\text{ }4 \right),\text{ }\left( 5,\text{ }5 \right),\text{ }\left( 5,\text{ }6 \right),\text{ }\left( 6,\text{ }5 \right),\text{ }\left( 6,\text{ }6 \right) \right]\]

    \[P\left( B \right)\text{ }=\text{ }\left[ P\left( 4 \right).P\left( 6 \right)\text{ }+\text{ }P\left( 6 \right).P\left( 4 \right)\text{ }+\text{ }P\left( 5 \right).P\left( 5 \right)\text{ }+\text{ }P\left( 5 \right).P\left( 6 \right)\text{ }+\text{ }P\left( 6 \right).P\left( 5 \right)\text{ }+\text{ }P\left( 6 \right).P\left( 6 \right) \right]\]

=

    \[0.3\text{ }x\text{ }0.1\text{ }+\text{ }0.1\text{ }x\text{ }0.3\text{ }+\text{ }0.1\text{ }x\text{ }0.1\text{ }+\text{ }0.1\text{ }x\text{ }0.1\text{ }+\text{ }0.1\text{ }x\text{ }0.1\text{ }+\text{ }0.1\text{ }x\text{ }0.1\]

=

    \[0.03\text{ }+\text{ }0.03\text{ }+\text{ }0.01\text{ }+\text{ }0.01\text{ }+\text{ }0.01\text{ }+\text{ }0.01\text{ }=\text{ }0.10\]

A and B both events will be independent if

    \[P(A\cap ~B)\text{ }=\text{ }P\left( A \right).P\left( B \right)\]

…. (i)

And, here

    \[(A\cap ~B)\text{ }=\text{ }\left\{ \left( 5,\text{ }5 \right),\text{ }\left( 6,\text{ }6 \right) \right\}\]

So,

    \[P(A\cap B)\text{ }=\text{ }P\left( 5,\text{ }5 \right)\text{ }+\text{ }P\left( 6,\text{ }6 \right)\text{ }=\text{ }P\left( 5 \right).P\left( 5 \right)\text{ }+\text{ }P\left( 6 \right).P\left( 6 \right)\]

=

    \[0.1\text{ }x\text{ }0.1\text{ }+\text{ }0.1\text{ }x\text{ }0.1\text{ }=\text{ }0.02\]

From equation (i) we get,

    \[0.02\text{ }=\text{ }0.20\text{ }x\text{ }0.10\]

    \[0.02\text{ }=\text{ }0.02\]

Therefore, A and B are independent events.