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Probabilities & Z-Scores w/ Graphing Calculator quiz

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  • What function on the TI-84 calculator is used to find the probability for a given z-score?
    The normalcdf function is used to find the probability for a given z-score on the TI-84 calculator.
  • How do you input negative infinity as a lower bound in the TI-84 calculator?
    You input negative infinity as -1E99 (negative one times ten to the ninety-ninth power) as the lower bound.
  • What are the default values for mu and sigma when using the normalcdf function for standard normal distribution?
    The default values are mu = 0 and sigma = 1 for the standard normal distribution.
  • Which function on the TI-84 calculator finds the z-score for a given probability?
    The inverse norm function is used to find the z-score for a given probability.
  • When finding the probability that z is less than a value, which area under the curve are you calculating?
    You are calculating the area to the left of the given z-score.
  • How do you find the probability between two z-scores using the TI-84?
    Set the lower bound to the smaller z-score and the upper bound to the larger z-score in the normalcdf or shade normal function.
  • What extra step is needed on a regular TI-84 Plus (not CE) when given a right-tail probability?
    You must convert the right-tail probability to a left-tail probability by subtracting it from 1 before using inverse norm.
  • What does the shade normal function do on the TI-84 calculator?
    The shade normal function visually displays the area under the curve corresponding to the probability on the graph.
  • If you are given P(z > a) = 0.3409, what value do you input for a left-tail calculation?
    You input 1 - 0.3409 = 0.6591 for the left-tail calculation.
  • What is the result of using inverse norm with an area of 0.0853?
    The result is a z-score of approximately -1.37.
  • Why is it helpful to sketch a graph before using the calculator for probability problems?
    Sketching a graph helps visualize the area or probability being calculated and reduces the chance of mistakes.
  • What does the normalcdf function output when you enter the bounds and parameters?
    It outputs the probability (area under the curve) between the specified bounds.
  • How do you clear the graph on the TI-84 after using the shade normal function?
    Press 'Clear' to return to the main screen, then use 'Clear Draw' to wipe the graph.
  • What does the TI-84 Plus CE allow you to specify in the inverse norm function that the regular TI-84 Plus does not?
    The TI-84 Plus CE allows you to specify whether the area is to the left, center, or right of the z-score.
  • What is the probability between z = -1 and z = 1 according to the calculator?
    The probability is approximately 0.6827.