Question

8. (i) Write the cardinal number of the set A, where A = {x : x is a two digit number, sum
of whose digits is 8).
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Answer 1

Answer: n(A)=4

Step-by-step explanation:

A={x : x is a two digit number whose sum of digits is 8}

Now we have to find those numbers whose sum results 8. Lets say, a+b=8. Now,

a+b=8

a=1, b=7     =17

a=2, b=6    =26

a=3, b=5     =35

a=4, b=4      =44

Therefore,

A={17,26,35,44}

n(A)= 4

Answer 2

Answer: 8

Step-by-step explanation:

We have to choose the digits whose sum will be 8

So, we chose

1+7= 8

2+6=8

3+5=8

4+4=8

Digits - 1,7,2,6,3,5,4,4

A={1,2,3,4,4,5,6,7}

Cardinal number or number of digits= 8 ✓

Hope it will solve your problem friends