Example 1: use of and a graphing calculator to find normal probabilities
a swimmer named amy specializes in the 50-meter backstroke. in competition, her mean time for the event is 39.7 seconds, and the standard deviation of her times is 2.3 seconds.
assume that amy’s times are approximately normally distributed.
a. estimate the probability that amy’s time is between 37 and 44 seconds.
b. using z-scores and a graphing calculator and rounding your answers to the nearest thousandth, find the probability that amy’s time in her next race is between 37 and 44 seconds.
c. estimate the probability that amy’s time is more than 45 seconds.
d. using z-scores and a graphing calculator and rounding your answers to the nearest thousandth, find the probability that amy’s time in her next race is more than 45 seconds.
e. what is the probability that amy’s time would be at least 45 seconds?
f. using z-scores and a graphing calculator and rounding your answers to the nearest thousandth, find the probability that amy’s time in her next race is less than 36 seconds.

Two customers went to a post office. first customer paid $12 for 14 and 5 envelopes the second paid 24.80 for 10 postcards and 15 envelopes. what is cost of each envelope?

Se tiene en una caja de canicas 10, 4 blancas y 6 negras ¿cual es la probabilidad que en 2 extracciones con reemplazo sean blancas? ¿cual es la probalidad que en 2 extracciones sin reemplazo sean negras?

Design an er diagram for keeping track of information about votes taken in the u. s. house of representatives during the current two-year congressional session. the database needs to keep track of each u. s. state's name (e. g., texas', new york', california') and include the region of the state (whose domain is {northeast', midwest', southeast', southwest', west'}). each congress person in the house of representatives is described by his or her name, plus the district represented, the start date when the congressperson was first elected, and the political party to which he or she belongs (whose domain is {republican', democrat', 'independent', other'}). the database keeps track of each bill (i. e., proposed law), including the bill name, the date of vote on the bill, whether the bill passed or failed (whose domain is {yes', no'}), and the sponsor (the congressperson(s) who sponsored - that is, proposed - the bill). the database also keeps track of how each congressperson voted on each bill (domain of vote attribute is {yes', no', abstain', absent'}). additional information: