Your answer will be 7.50. What I did was take 1.25 and times it by 6.
Let p be 0.831 denote the percentage of defective welds and q be 0.169 denote the percentage of non-defective welds.
Using the binomial distribution, we want all three to be defective.


I'm assuming that when you wrote "(7x/2-5x+3)+(2x/2+4x-6)," you actually meant "<span>(7x^2-5x+3)+(2x^2+4x-6). Correct me if I'm wrong here.
</span><span>+(7x^2-5x+3)
</span><span>+(2x/2+4x-6)
-------------------
=9x^2 - x - 3 (answer) </span>
They're both equal. The zero in 95.580 doesn't matter in this comparison.