Question

Suppose that m and n are two independent works .



If ways to do a work m is x and number of ways to do a work n is y then number of ways in which both work (m and n ) can be done is xy .

x={2,3,4,5,6,7,8,9}
y={0,1}
z={0,1,2,3,4,5,6,7,8,9}



Before 1990, telephone area codes in the United States were three-digit numbers of the form xyz. Shown above are sets X, Y, and Z from which the digits x, y, and z, respectively, were chosen.


Q.1 how many possible area codes were there ?





Q.2 how many such area codes are possible which have two same digits ( repetitive digit )

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Answer 1

Answer:

Suppose that m and n are two independent works .

If ways to do a work m is x and number of ways to do a work n is y then number of ways in which both work (m and n ) can be done is xy .

x={2,3,4,5,6,7,8,9}

y={0,1}

z={0,1,2,3,4,5,6,7,8,9}

Before 1990, telephone area codes in the United States were three-digit numbers of the form xyz. Shown above are sets X, Y, and Z from which the digits x, y, and z, respectively, were chosen.

Q.1 how many possible area codes were there ?

Q.2 how many such area codes are possible which have two same digits ( repetitive digit )

Answer 2

Answer:

hope this helps u........................