Question

compound events
question id : 59126
6 of 10
alison is learning how to walk. 50% of the time that she takes a step she falls down. her older brother wants to design a simulation to find the probability she will fall down 5 out of the next 7 times she tries to take step.
which simulation design has an appropriate device and a correct trial?
a roll a die letting 1 represent alison falling and 2-6 represent alison not falling. roll the die five times.
b roll a die letting 1 represent alison falling and 2-6 represent alison not falling. roll the die seven times.
c let heads represent alison falling down and tails representing alison not falling down. flip the coin five times.
d let heads represent alison falling down and tails representing alison not falling down. flip the coin seven times.

Explanation:

1. First, match the probability: Alison has a 50% chance of falling per step. A coin flip (Heads/Tails) has exactly a 50% probability for each outcome, which matches. A die roll with 1 as a fall and 2-6 as no fall gives a $\frac{1}{6}$ chance of falling, which does not match the 50% probability.
2. Next, match the number of trials: We need to simulate 7 steps, so the device (coin) must be flipped 7 times. Flipping 5 times would simulate only 5 steps, which is incorrect.

Answer:

D. Let Heads represent Alison falling down and Tails representing Alison not falling down. Flip the coin seven times.