Interactive practice questions
The literacy rate of a population is used to help measure the level of development of a country. The average literacy rate in a particular country is $59%$59%, and the standard deviation is $5%$5%. The literacy rate varies from place to place within the country.
Find the literacy rate that is $3$3 standard deviations above the mean. Leave your answer as a percentage.
Find the literacy rate that is $2$2 standard deviations below the mean. Leave your answer as a percentage.
The following table shows the marks obtained by a student in two subjects.
Dylan scored $90%$90% with a $z$z-score of $2$2 in English, and $78%$78% with a $z$z-score of $4$4 in mathematics.
In which subject was his performance better, relative to the rest of his class?
Jenny scored $81%$81% with a $z$z score of $-2$−2 in English, and $72%$72% with a $z$z score of $-4$−4 in Mathematics. In which subject was her performance better, relative to the rest of the class?