The ratio of a two-digit natural number to a number formed by reversing its digits is 4: 7. The number of such pairs is
5
4
3
2
Answer is (b). Let the ten's digit of two digit number ab be 'a' and unit’s digit be 'b'. So the number will be of the form 10a + b. After reversing the digits the number will be 10b + a. By the condition given in question we have (10a+b)/(10b+a)=4/7 which means a/b=1/2 So by putting the values, total possible pairs (12, 21), (24, 42), (36, 63), (48, 84). Thus, four pairs are possible.
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