Answer:
Student 1 has the correct answer
Student 2 started of OK but then divides the number of white marbles by the number of non-white marbles, which is incorrect.
Student 3 reports a probability larger than 1 which is impossible. Also the answer is not in percentages.
Answer:
x = ±3
Step-by-step explanation:
2 = |x| - 1
Add 1 to both sides: |x| = 3
⇒ x = ±3
By the fundamental theorem of calculus,

which means
3 yards = $7.47
1 yard = $(7.47 ÷ 3) = $2.29
2 yards = $ (2.29 × 2) = $5.58
$ (7.47 + 5.58) = $ 13.05