**8/08/2014
**The
numbers below denote the horsepower
of n
= 38
vehicles.

65,
65, 68, 68, 69, 70, 71, 71, 75, 78, 80, 80, 85, 88, 90, 90, 95, 97,
97, 103, 105, 109, 110, 110, 115, 115, 115, 120, 125, 125, 129, 130,
133, 135, 138, 142, 150, 155

a) Find the 1^{st}
and
3^{rd}
Quartiles.
Interpret the 1^{st}
Quartile.

b)
Find the 68th and interpret
it.

c)
A vehicle with a horsepower of 103hp lie in what percentile?
Interpret it.

**Scroll
down for the solution.**

**8/08/2014
**Solution.
a)
For Q1, 0.25·38 = 9.5 → 10th value => 78hp

Interpretation: A car with a horsepower of 78 corresponds to the 25th percentile which means that 25% of all [given] vehicles have a horsepower of 78hp

Q3 = 129hp

b) 0.68·38 = 25.84 ~ 26th value → 115hp

Interpretation: A car with a horsepower of 115 corresponds to the 68th percentile which means that 68% of all [given] vehicles have a horsepower of 115hp

Do this yourselves! Find the 91st percentile.

c) P(X

Interpretation: A car with a horsepower of 103 corresponds to the 52.63rd percentile which means that 52.63% of all [given] vehicles have a horsepower of 103hp