Which of the following data sets would be suitable to determine the total percentage of absences in a school?
Three different toys are stored in a warehouse. There are 15 000 toys in total and the number of each is shown in the table.
|Kinds of Stones||Bears||Dolls||Cars|
|Number of Stones||2 000||6 000||7 000|
A stratified sample of all the toys is taken and 420 cars are selected. Calculate the total number of toys in the sample.
An experiment has been designed to investigate the alleged benefits of using a fabric softener. In the experiment the participants are divided into two groups: one group gets laundry washed using a fabric softener, while the other gets laundry washed without using any fabric softener. All of the participants laundry is washed over several weeks and none of the participants know how their laundry has been washed.
Which of the following is the type of the experiment?
Which of the following is the treatment variable?