Edexcel S2 2021 June — Question 3

Exam BoardEdexcel
ModuleS2 (Statistics 2)
Year2021
SessionJune
TopicContinuous Probability Distributions and Random Variables
TypeFind mode of distribution

  1. The continuous random variable \(Y\) has the following probability density function
$$f ( y ) = \begin{cases} \frac { 6 } { 25 } ( y - 1 ) & 1 \leqslant y < 2
\frac { 3 } { 50 } \left( 4 y ^ { 2 } - y ^ { 3 } \right) & 2 \leqslant y < 4
0 & \text { otherwise } \end{cases}$$
  1. Sketch f(y)
  2. Find the mode of \(Y\)
  3. Use algebraic integration to calculate \(\mathrm { E } \left( Y ^ { 2 } \right)\) Given that \(\mathrm { E } ( Y ) = 2.696\)
  4. find \(\operatorname { Var } ( Y )\)
  5. Find the value of \(y\) for which \(\mathrm { P } ( Y \geqslant y ) = 0.9\) Give your answer to 3 significant figures.