A single female flea can consume up to $15$ times her body weight in blood during her adult life. Under normal circumstances, the adult female will live up to three weeks. A female flea can consume about $1.4\times10^{-5}$ liters of blood per day. If a dog has $50$ female fleas, how many liters of blood do the fleas consume in a week? Write your answer in scientific form.
Two students, Juraj and Tom, solved this problem. Each of them solved the problem on his own way.
Juraj:
(1) $50$ female fleas consume $50 \times 1.4 \times 10^{-5}\ l=70\times10^{-5}\ l$ of blood per day.
(2) In a week, $50$ female fleas consume $7\times70\times10^{-5}\ l=490\times10^{-5}\ l$ of blood.
(3) In scientific form, $490\times10^{-5}\ l=4.9\times10^{-3}\ l$.
Tom:
(1) In a week, a female flea consumes $7\times 1.4 \times 10^{-5}\ l=9.8\times10^{-5}$ of blood.
(2) $50$ female fleas consume $50 \times 9.8 \times10^{-5}\ l=490\times10^{-5}\ l$ of blood week.
(3) In scientific form $490\times10^{-5}\ l=4.9\times 10^{-7}\ l$.
Which of the following statements is true?
Tom solved the first two steps correctly, but the third step is wrong.
Juraj correctly solved the first two steps, but the third step is wrong.
Tom solved the problem correctly.
Both made a mistake in the third step.
Juraj’s solution is correct. Tom made a mistake in step (3). Tom incorrectly shifted the decimal point when converting a number to a scientific format.