Scatter graphs and correlationIB MYP Maths Extended: Flashcards

Exam questions on Scatter graphs and correlation

1. A café in Cape Town records the maximum temperature $x$ (in °C) and the number $y$ of cold drinks sold on six days: $(18,40)$, $(21,55)$, $(24,68)$, $(27,85)$, $(30,98)$, $(33,115)$. A line of best fit for the data passes through $(20,45)$ and $(30,100)$.
   Find the gradient of the line of best fit and explain what it means in this context.2 marks
2. Eight students record the hours $x$ of revision they did before a test and the number $y$ of mistakes they made: $(1,19)$, $(2,16)$, $(3,14)$, $(4,13)$, $(5,10)$, $(6,8)$, $(7,7)$, $(8,4)$. A line of best fit for the data passes through $(2,16)$ and $(6,8)$.
   Use the line of best fit to estimate the number of mistakes made by a student who revises for 5.5 hours.2 marks
3. A road-safety team in Dubai records the speed $x$ (in km/h) and the braking distance $y$ (in metres) of a car in six trials: $(20,8)$, $(30,14)$, $(40,19)$, $(50,25)$, $(60,30)$, $(70,36)$. A line of best fit for the data passes through $(20,8)$ and $(70,36)$.
   Find the mean speed and the mean braking distance, and write down the coordinates of the mean point, through which a line of best fit should pass.3 marks