Bunuel
If a and b are positive integers, is a/b < 9/11 ?
(1) a/b < 0.818
(2) b/a > 1.223
To compare two fractions:
Multiply the numerator in each fraction by the denominator in the other.
The numerator that yields the bigger product belongs to the bigger fraction.
Alternate solution:
Is a/b < 9/11?
Statement 1: a/b < 818/1000Comparing \(\frac{818}{1000}\) and \(\frac{9}{11}\), we get:
818*11 = 818(10+1) = 8180 + 818 = 8998
9*1000 = 9000
Since the numerator for 9/11 yields the greater product:
818/1000 < 9/11
Since a/b < 818/1000 < 9/11, we get:
a/b < 9/11
Thus, the answer to the question stem is YES.
SUFFICIENT.
b/a > 1.223 --> \(\frac{b}{a}\) > \(\frac{1223}{1000}\) -->\(1000b > 1223a\) --> \(\frac{1000}{1223}\) > \(\frac{a}{b}\) --> \(\frac{a}{b}\)< \(\frac{1000}{1223}\)
Statement 2: a/b < 1000/1223Comparing \(\frac{1000}{1223}\) and \(\frac{9}{11}\), we get:
1000*11 = 11000
9*1223 = (10-1)1223 = 12230-1223 = 11007
Since the numerator for 9/11 yields the greater product:
1000/1223 < 9/11
Since a/b < 1000/1223 < 9/11, we get:
a/b < 9/11
Thus, the answer to the question stem is YES.
SUFFICIENT.