Because you have the formula, it is pretty easy to answer. l=prt, so you plug in p, r, and t to get l. 1) l = 8000 times 0.6 times 1 2) you would then get 4800 times 1 3) Now you have 4800 because 4800 times 1 is 4800.
No this is not a valid reference because those were 20 random families, if he does another test the next twenty families 50% of them could attend the party. Too much chance to be valid.
