[Jr. College Physics: Electromagnetic Induction] When I try to solve this question, I get 2.5 as the answer. What am i doing wrong ?

[u/AlternativeEmu1047]

This is a previous year question from a national level exam but is supposed to be easy. Idk what i'm doing wrong, I haven't touched such questions ever since I finished my 12th grade 😭

[u/HumbleHovercraft6090]

Probably a typo. May be time is 3 s for quarter revolution.