Explain why a data is collected from a sample and not a census? b) To find the percent of Grade 7 students who know the multiplication tables.

c) Rita researched accident statistics in her community. She learned that, in the past year,
30 people were injured in car accidents and 10 people were injured in motorcycle
accidents. Rita inferred, “It is safer to ride a motorcycle than it is to drive a car.”
Is Rita’s inference valid? Explain.

Sara sells beaded necklaces she makes a profit of 4 dollars pn every neclace she sells which table represents the profit sara makes

Monthly water bills for a city have a mean of $108.43 and a standard deviation of $32.09. find the probability that a randomly selected bill will have an amount greater than $155, which the city believes might indicate that someone is wasting water. would a bill that size be considered unusual?

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.