In mary's first math test she scored 87%. the mean and standard deviation for the class were 71% and 18% respectively. in her second math test, mary scored 66%. the mean and standard deviation for the class were 53% and 14% respectively. in which test did mary do better relative to the rest of the class? explain your reasoning. (hint: find the z-scores corresponding to her two test scores.)

Step-by-step explanation:

Since your population are the students in math class, you can use the z-score formula in order to comparing the two math test scores. Where is the mean for the class, is the standars deviation and x is Mary score.

For the first test , so ,.

For the second test , so ,

Mary do better in the second test, relative to the rest of the class (because  , it means the second score is nearer to the mean score of the class than the first one )  

5

step-by-step explanation:

54 km / hours

step-by-step explanation:

we need to convert seconds to hours

60 seconds = 1 minutes

60 minutes = 1hour

15 m         60 second   60 minutes

  * *         = 54000 meters/ hour

second     1 minute             1 hour

now we need to convert meters to km

1000 m = 1 km

54000 m       1 km

*   = 54 km / hours

hour               1000m