HistogramsIB MYP Maths Extended: Mind map

Exam questions on Histograms

1. A café in Seoul records how long $t$ minutes 70 customers wait to be served. The results are: $0<t\le2$: 8 customers; $2<t\le5$: 21 customers; $5<t\le10$: 30 customers; $10<t\le20$: 11 customers. The data is to be shown in a histogram.
   Find the frequency density of the class $10<t\le20$.2 marks
2. A student investigates classes of different widths that each have frequency 12. The class $0<x\le1$ (width 1) has frequency density 12. The class $1<x\le3$ (width 2) has frequency density 6. The class $3<x\le7$ (width 4) has frequency density 3. The class $7<x\le15$ (width 8) has frequency density 1.5.
   Use the rule to find the frequency of a class of width 6 with frequency density 2.5, and the frequency density of a class of width 3 with the same frequency.2 marks
3. A histogram shows the ages $a$ in years of the people who visited a museum in Cape Town on one day. The frequency densities are: $0\le a<10$: 2.4; $10\le a<20$: 3.5; $20\le a<40$: 4.2; $40\le a<70$: 1.5.
   Find the number of visitors in each class and the total number of visitors.3 marks