A principal wanted to survey students who took a standardized college entry exam about how prepared they felt for the exam. The principal put together a bag of marbles. There was 1 marble for each student, and 20 of the marbles
were red. Each student chose a marble, and those who chose the red marbles took the survey. Which sampling
method was used?

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step-by-step explanation:

answers

\3. yes the presentation (i.e. odd numbers being written as differences of two squares) is possible for all odd natural number however the presentation may not be unique. for example,  57=112−82=292−28257=112−82=292−282.

\4. 2 can't be written as a difference of two squares because 4-1=3 and 1-1=0 and the difference of squares grows to integers larger that 3.

can i get some in proving questions 1 and 2?