Three recent college graduates have formed a partnershlp and have opened an advertising firm. Thelr first project consists of activities

listed in the following table. Use Table B$.$

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a$.$ What is the probability that the project can be completed in $24$ days or less? In $21$ days or less? $($Round your $t_e$ and $z$ values to $2$

decimal places and "Standard deviation" to $3$ decimal places. Round your final answers to $4$ decimal places.$)$

b$.$ Suppose it is now the end of the seventi.day and that activtles A and $B$ have been completed while activity $D$ is $50$ percent

completed. Time estimates for the completion of activity $D$ are $5,6,$ and $7.$ Activities $C$ and $H$ are ready to begin. Determine the

probability of finishing the project by day $24$ and the probability of findsing by day $21.($Round your intermedlate calculations to $3$

decimal places and final answers to $4$ decimal plates.$)$