Programme For International Student Assessment Pisa / Sample Math Passage 7: Lighthouse


Lighthouses are towers with a light beacon on top. Lighthouses assist sea ships in finding  their way at night when they are sailing close to the shore. 

A lighthouse beacon sends out light flashes with a regular fixed pattern. Every lighthouse  has its own pattern. 

In the diagram below you see the pattern of a certain lighthouse. The light flashes alternate  with dark periods. 


 

Non MCQ Question:

In the diagram below, make a graph of a possible pattern of light flashes of a lighthouse that sends out  light flashes for 30 seconds per minute. The period of this pattern must be equal to 6 seconds. 





For how many seconds does the lighthouse send out light flashes in 1 minute?

12
4
20
24

Which of the following could be the period of the pattern of this lighthouse?

3 seconds
12 seconds
5 seconds
2 seconds