A marketing firm determined that, of 200 households surveyed, 80 used neither Brand A nor Brand B soap, 60 used only Brand A soap, and for every household that used both brands of soap, 3 used only Brand B soap. How many of the 20 households surveyed used both brands of soap?
a) 15
b) 20
c) 30
d) 40
e) 45
I'm trying to use the formula: A + B - Both + Neither = 200
That gives us:
60 + 3x - x + 80 = 200
2x = 60
x = 30
But the answer is 15. Am I using the formula incorrectly?
a) 15
b) 20
c) 30
d) 40
e) 45
I'm trying to use the formula: A + B - Both + Neither = 200
That gives us:
60 + 3x - x + 80 = 200
2x = 60
x = 30
But the answer is 15. Am I using the formula incorrectly?
