Mr. R.’s World of Math

“Look! Regina has two noses!” we all yelled.
Ms. Curie smiled, and said, “It’s true. Regina now has two noses!”

Regina looked terrified, and reached to feel her face. She screamed when she realized she had two noses.
“I don’t want two noses! What did you do to me?” cried Regina.
“Don’t worry,” said Ms. Curie, “I’ll change you back at the end of the lesson. Now do me a favor and smell this chocolate bar for me.”
Regina looked so scared, and we all felt bad for her, but when she smelled the chocolate bar, she smiled.
“I can smell twice as good as ever,” she said, “and the chocolate smells so amazing.”
“That’s correct, Regina,” said Ms. Curie, “and all I did was change your DNA a little bit, so that your body would grow an extra nose.”
“That little laser light can change your DNA?” asked Jake. 
“Sure,” said Ms. Curie, “a little D here, some N here, a bit of A here, and some gene splicing there, it’s all good,” she laughed, “Now, do I have another volunteer?”
Nobody raised their hand.
“I think you’ve given them a pretty big scare,” I said, “Maybe you should turn Regina back to a single nosed student first.”
“Yes, perhaps you’re correct,” said Ms. Curie, and she took the little laser and pressed it up against Regina’s arm. Regina started glowing and spinning around again. She spun faster and faster and when she stopped she only had one nose again.
The students cheered, and Regina thanked Ms. Curie for subtracting one of the noses she had added.
“Ok, now do I have another volunteer?”
Again, nobody raised their hand.
“I guess they’re still a little scared,” I said.
“Oh, there’s nothing to be scared of,” said Ms. Curie, “Why don’t you be my next victim…I mean volunteer,” she said to me.
“Yeah, Mr. R., it’s all for science,” laughed Zander.
I must admit, I was a little nervous about what Ms. Curie might do to me, but I agreed and walked up to the front of the classroom. She put the little laser against my arm and I saw everything start spinning around.
It was hard to hear anything, but I think I heard Jenna scream, “Hey, look, Mr. R.’ is on a super-fast merry-go-round!”
“Yeah, he must be dizzy!” laughed Jackie.
When things stopped spinning, I felt really weird. It felt as if my face was pulling my entire head toward the ground, and I saw the students laughing harder than I’d ever seen them laughing. 

The students laughed 120% longer than usual. If they usually laughed for 7 minutes, how long had they laughed for?