Hint: It's not just the vowels that have a problem.
Answer: H, S and T.
It should read:
Can you tell what is wrong with this paragraph? At first glance you may think that just the vowels have problems, but no! Three consonants also have problems, they have been replaced with the letter R, but which ones are they?
Which is greater:
the number of seconds in a year or miles light can travel in 3 minutes?
Hint: Light travels at around 186,000 miles in a second.
Answer: Miles light can travel in 3 minutes.
There are 31,536,000 seconds in a year and light can travel 33,530,831 miles in 3 minutes (roughly).