guest Wrote:I totally no idea ? who can help me this question ?
i know ABI= a+b+i -ab but i still can not figure out?
if you know that formula, just plug into it.
for onlookers:
"ABI" is, basically, "everyone total".
"a" is "has tv"
"b" is "has car"
"i" is "has neither"
"ab" is "has both"
by the way, this is a prime illustration of why using the double-set matrix is better than using formulas. we have a user who knows the formula cold but is STILL confused by it; that will not happen with the double set matrix.
you're looking for "i" (in your terms).
using your formula,
3000 = 2980 + 2970 + i - "ab"
the problem is, you don't know "ab" (the number who have both). this number could range anywhere from 2950 to 2970, but it's sufficient just to realize that it can have more than one value.
since i depends on ab, INSUFFICIENT.
--
this problem is easier to visualize with the double set matrix.