If the pair of opposite sides are both parallel and congruent, the other two sides will have to fit in between the two lines. That will make the other two sides both parallel and congruent, so the quadrilateral is a parallelogram.
A parallelogram is a quadrilateral. A parallelogram has two pairs of opposite parallel sides. The opposite parallel sides are equal in length and are congruent.
The interquartile range is from Q1 to Q3 and to get this you have to subtract Q2 by Q3. The 10 units represent that only 10 units are fit in the given range.
