It’s biased because he is asking people who left a country concert and usually people who go to concerts go because it’s the type of music that they like, so the chances of someone saying they like a different kind of music probably won’t happen.
To find whether the volume would be doubled when the radius is,we can find the volume of the two balloons.
The formula of a sphere is:

Let's take 丌 as 3.14
The volume of the balloon with 4cm radius:

The volume of the balloon with 8cm radius:

As we can see,
267.94668 × 2 = 535.89 ≠2145.56
Thus,she wouldn't discover that the volume is twice as big when the radius is doubled.
Hope it helps!
Jada has saved 60% of $60. This is a percent of number question.
First we need to know 60% of $60
Change the percent to a decimal and multiply.
.60(60) =$36 saved so far.
The ones where I had to dance. For me, I am not a big fan of dancing and we had to do the la cha cha as our warm ups everyday. It was so weird. I think I rather do 5 push-ups, 10 sit-ups and jumping jacks for a warm up instead. :V