Instead of "W ciągu 15 sekund, jakie są 12 miesięcy w roku?" it should be "W ciągu 15 sekund, jakich jest 12 miesięcy w roku?"
Your version is wrong as you used "jakie są" instead of "jakich jest". "Są" would be normally fine as it is used for plural. In this case though it is not. "Jakich" (it means "which" in english) corresponds to plural and "jest" corresponds to singular. It should be so as "jest" corresponds to each of the months separately, not as a whole group. I know it sounds weird and most of the polish people would probably be confused too :)
If you want to keep the "jakie są", you should paraphrase to "W ciągu 15 sekund, jakie są miesiące w roku?". Now, "jakie są" would relate to "months" and not "12 months". 12 is a numeral and numerals have different rules in grammar (the one mentioned above was an example).
I hope I helped :)
by zagrać w tenisa,
źle odbiła piłkę,
trafiła go w penisa ;)
w 13 sekund, ciekawy quiz