*Reference: Study Notes - Constructing a Stem-and-Leaf Diagram (p20)*
**Scenario:**

Because of Singapore's geographical location, we are impacted by smoke haze when there are forest fires in the region and the prevailing southwest monsoon winds blow the smoke from the fires in our direction, which usually occur in the period of May to October.

However, Singapore experiences the worst haze situation in June this year.

We are going to analyse how different the quality of air in each zone, compared to the overall quality of air in Singapore.

**The Task:**
*(A) Gathering Data*
1. Each team will be assigned to

**plot a stem-and-leaf diagram** for the PSI value of and

**assigned zone** (north, south, east, west), against the

**overall Singapore PSI value**.

2. Retrieve the data from the NEA website:

Resource:

http://app2.nea.gov.sg/anti-pollution-radiation-protection/air-pollution/psi/historical-psi-readings/year/2013/month/6/day/1
3. Your reference time for everyday will be

**8 am**.

As the overall Singapore PSI value is presented in a range. Use the

**mid-point** for the plotting.

*(B) Organising and Presenting Data*

4. The leaves on the left should be the data of the "Overall Singapore PSI value" whereas those on the right would be that of the 'zone' that your team has been assigned to.

5. Remember to include the "Key" to both sets of data.

*(C) Analysing Data*
6. Using the Stem-and-Leaf diagram, find the

**mean, median** and

**mode** of both sets of data.

Show the working to obtain the mean of each set of data clearly.

7. For each set of data, attempt to use the mean, median and mode to discuss the haze situation over the month.

8. Make a comparison of these 2 sets of data, and comment the haze situation at the zone (that your team has been assigned to) and the overall value.

*Below is the chart that represents the number of hotspots in Sumatra (from 6 June to 5 July).*
9. Make reference to the Overall Singapore PSI values for the month, what observations can you draw between Singapore's PSI value and the hotspots detected in Sumatra? Comment on your observations.

**Other useful links**

**Submission:**
1. Complete the task on the A3 size paper provided (during lesson).

Remember to include your Group Number, Team Number & Name of members of the team in the same page.

Criteria for assessment: Mathematically correct (concept and presentation) and aesthetic design

2. Put up your solution on the noticeboard at the back of the classroom by next Monday

**15 July 2013 (Monday)**