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

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.