Q23 of 65 Page 122

Find all pairs of consecutive odd positive integers both of which are smaller than 10 such that their sum is more than 11.

Let us assume x be the smaller of the two consecutive odd positive integers

∴ Other integer = x + 2


It is also given in the question that, both the integers are smaller than 10


∴ x + 2 < 10


x < 8 (i)


Also, it is given in the question that sum off two integers is more than 11


∴ x + (x + 2) > 11


2x + 2 > 11



x > 4.5 (ii)


Thus, from (i) and (ii) we have x is an odd integer and it can take values 5 and 7


Hence, possible pairs are (5, 7) and (7, 9)


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