The probability that exactly x number of cars will be defective is given by
[tex]P(X)={ ^nC_xp^x(1-p)^{n-x}[/tex]
Here p = 0.087, n = 7, x = 3
[tex]P(3)={ ^7C_3(0.087)^3(1-0.087)^{7-3}} \\ \\ =35(0.087)^3(0.913)^4=35(0.000658503)(0.694837) \\ \\ =0.016[/tex]