Mr. R.’s World of Math

Carlos’ grandfather continued to show us different controls, but as he did, nobody realized that Matthew had used his phone to learn the buttons to begin the launch sequence. He snuck over to the controls and started to press the buttons.
Suddenly, we all heard a voice say, “Launch sequence initiated.”
We saw Carlos’ grandfather’s face fill with surprise and then fear, “What? Who pressed the buttons?” he screamed, “I can’t stop the launch sequence once it’s started!”
“What are we going to do?” I screamed, “I can’t have the students launch into space! They didn’t even have lunch yet!”
“There’s no choice!” yelled Carlos’ grandfather, “Everyone strap yourselves into a seat! Quick!”
We all ran to a seat and buckled straps across our bodies.
“OK, let’s make the most of this!” said Carlos’ grandfather and we saw him smile a little bit.
We heard the countdown 10-9-8-7-6-5-4-3-2-1…Lift Off.
The next thing we knew, we felt a rumbling explosion underneath us, and then we started lifting into the sky.
“I feel so heavy I can barely move my arms!” yelled Jenna,
“That’s the gravitational pull increasing as we increase in speed!” said Carlos’ grandfather, and then he smiled.
He seemed very happy for someone who just got accidentally launched into space with a rocket full of kids. The rest of us were as scared as we’ve ever been.
As we looked out the windows, we saw Earth getting smaller and smaller below us.
“How far up are we?” asked Zander.
“About 50 miles!” said Carlos’ grandfather.
“Woah! That’s high up!” I said.
“It looks cool,” said Jake as we began to see the curve of the Earth’s horizon.
“Yes, it’s so beautiful up here,” said Carlos’ grandpa, “I’ve always wanted to see this view!”
Suddenly something strange happened. We all felt really light in our seats.
“Want to try something fun?” asked Carlos’ grandfather.
“Yeah,” said Matthew.
“OK, unbuckle your restraints,” said Carlos’ grandfather.
We all unbuckled, and we started floating around. We were floating through the air bumping into each other.
Jenna started doing summersaults, and Jackie sprayed some water out of her water bottle. The droplets were floating and we went around eating them out of the air.
“This is the best day of school ever!” yelled Matthew as he floated around.
Carlos’ grandfather opened a bag of M&Ms and dumped them out. They began floating and the students were grabbing them with their mouths!
“OK, we have only 2 minutes left,” said Carlos’ grandfather, everyone float over to the window.
We did and we all looked out.
“Whoa, Earth looks so cool from here. I can see like everything,” said Jackie.
“Yeah, Earth looks like a little blue marble.”
“Yeah, and everything that has ever lived, has lived on that marble, at least everything we know of,” I said.
“Yeah, we better not let anything bad happen to it, there’s nowhere else to go,” said Jenna. 
“That’s for sure,” said Carlos’ grandfather, “We’ve all gotta’ share that little blue rock. We’re all on the exact same trip around the sun!” Then he said, “Everyone float back to your seats and strap in, “We’ve used 36 of the 40 minutes of flight time we have…” 

What percentage of the flight time had they used?