Question

In a malaria epidemic, the number of cases diagnosed were as follows: 

Date July	1	2	3	4	5	6	7	8	9	10	11	12
Num	5	12	20	27	46	30	31	18	11	5	0	1

On what days do the mode and upper and lower quartiles occur?

Answer 1

Date	Number	C.f.
1	5	5
2	12	17
3	20	37
4	27	64
5	46	110
6	30	140
7	31	171
8	18	189
9	11	200
10	5	205
11	0	205
12	1	206

(i) Mode = 5^th July as it has maximum frequencies.

(ii) Total number of terms = 206 

Upper quartile = `206 xx 3/4`

= 154.5^th term

= 7^th July 

Lower quartile = `206 xx 1/4`

= 51.5^th term

= 4^th July