Find the probability of obtaining exactly four tails when flipping four coins. Express your answer as a fraction in lowest terms or a decimal rounded to the nearest millionth.

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.

X= 49; x = 4step 1: foilstep 2: equal both to 0step 3: find x individually

The answer is 109 times per second