Chapter 5 - Section 5.3 - Assess Your Understanding - Applying the Concepts - Page 285: 22a

$P(all~12~tests~will~be~positive)=0.99^{12}\approx0.886385$

$P(a~test~will~be~positive)=0.99$ Now, using the Multiplication Rule (see page 282): $P(all~12~tests~will~be~positive)=$ $=P(test~1~will~be~positive)\times P(test~2~will~be~positive)\times ... \\...\times P(test~12~will~be~positive) = $ $=[P(a~test~will~be~positive)]^{12}=0.99^{12}\approx0.886385$