Interquartile range calculation

Find the interquartile range (IQR = Q₃ - Q₁) by calculating both the upper and lower quartiles from the CDF.

3 questions

CAIE Further Paper 4 2024 June Q5
5 The continuous random variable \(X\) has cumulative distribution function F given by $$F ( x ) = \begin{cases} 0 & x < 2 ,
\frac { ( x - 2 ) ^ { 2 } } { 12 } & 2 \leqslant x < 4 ,
1 - \frac { ( 8 - x ) ^ { 2 } } { 24 } & 4 \leqslant x \leqslant 8 ,
1 & x > 8 . \end{cases}$$
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(c) Find the exact value of the interquartile range of \(X\).
CAIE Further Paper 4 2020 November Q6
6 The continuous random variable \(X\) has cumulative distribution function F given by $$F ( x ) = \begin{cases} 0 & x < 0
\frac { 1 } { 60 } \left( 16 x - x ^ { 2 } \right) & 0 \leqslant x \leqslant 6
1 & x > 6 \end{cases}$$
  1. Find the interquartile range of \(X\).
  2. Find \(\mathrm { E } \left( X ^ { 3 } \right)\).
    The random variable \(Y\) is such that \(Y = \sqrt { X }\).
  3. Find the probability density function of \(Y\).
    If you use the following lined page to complete the answer(s) to any question(s), the question number(s) must be clearly shown.
CAIE FP2 2018 June Q6
6 The continuous random variable \(X\) has distribution function given by $$\mathrm { F } ( x ) = \begin{cases} 1 - \mathrm { e } ^ { - 0.4 x } & x \geqslant 0
0 & \text { otherwise } \end{cases}$$
  1. Find \(\mathrm { P } ( X > 2 )\).
  2. Find the interquartile range of \(X\).