document.write( "Question 994671: a soldier hits her target with a probability of 3/10. How many times should she shoot at the target to ensure at least 70% chance of hitting the target? \n" ); document.write( "

Algebra.Com's Answer #613695 by Boreal(15235) $\"\"$ $\"About$

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You want 0.7, the probability of missing, to be raised to the x power to where it is less than 0.3, for at that point, there will be a greater than 70% chance of hitting the target.\r
\n" ); document.write( "\n" ); document.write( "0.7^x=0.3
\n" ); document.write( "ln both sides
\n" ); document.write( "x ln(.7)=ln(.3)
\n" ); document.write( "-0.357x= -1.204
\n" ); document.write( "x is greater than 3 but less than 4. Therefore, she has to shoot 4 times.
\n" ); document.write( "0.7^4=0.2401, and the probability of 4 misses in a row is 76%, and the probability of hitting the target is at least 70%. \n" ); document.write( "

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