Erfana Beevee Binte Hassan Shariff's answer to Troubled's Secondary 4 E Maths Singapore question.

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Erfana Beevee Binte Hassan Shariff
Erfana Beevee Binte Hassan Shariff's answer
241 answers (Tutor Details)
P(win in first race and lose in 2nd)=0.8x0.2=0.16
P(win first 3races) =0.8 x 0.8 x0.8=0.512
P(takes part in race for n weeks)
= P(wins in every race for n weeks)
= 0.8^n
P(lose race in 1st week) or p(win in first week and lose in 2nd week)
=0.2+ 0.8x0.2
=0.2+0.16
=0.36