In the following, a year corresponds to 1st of January of that year.
A study to determine the mortality rate for a disease began in 1980. The study chose 1000 males and 1000 females and followed them for forty years or until they died, whichever came first. The 1000 males chosen in 1980 consisted of 250 each of ages 10 to less than 20, 20 to less than 30, 30 to less than 40, and 40 to less than 50. The 1000 females chosen in 1980 also consisted of 250 each of ages 10 to less than 20, 20 to less than 30, 30 to less than 40, and 40 to less than 50.
The four figures below depict the age profile of those among the 2000 individuals who were still alive in 1990, 2000, 2010, and 2020. The blue bars in each figure represent the number of males in each age group at that point in time, while the pink bars represent the number of females in each age group at that point in time. The numbers next to the bars give the exact numbers being represented by the bars. For example, we know that 230 males among those tracked and who were alive in 1990 were aged between 20 and 30.
Solution
Understanding the set :-
- There is a study been conducted of 1000 males and 1000 females to determine the mortality rate
- This set contains 4 charts -
i) First chart consist of age of those 1000 males and females in 1990
ii) second chart consist of their ages in 2000s
iii) third chart consist of their ages in 2010
iii) Forth chart consist of their ages in 2020
| Age group (In 1980) | Males alive in 1990 | Males alive in 2000 | Males alive in 2010 | Males alive in 2020 |
|---|---|---|---|---|
| 10–20 | 230 | 180 | 150 | 140 |
| 20–30 | 235 | 205 | 165 | 125 |
| 30–40 | 210 | 160 | 90 | 50 |
| 40–50 | 190 | 100 | 25 | 5 |
This table consist of all 1000 males data over the years from the chart.
| Age group (In 1980) | Females alive in 1990 | Females alive in 2000 | Females alive in 2010 | Females alive in 2020 |
|---|---|---|---|---|
| 10–20 | 240 | 210 | 160 | 100 |
| 20–30 | 225 | 175 | 145 | 105 |
| 30–40 | 190 | 150 | 100 | 60 |
| 40–50 | 220 | 120 | 30 | 18 |
This table consist of all 1000 female data over the years from the chart.
| Age group (In 1980) | Males alive in 1990 | Males alive in 2000 | Males alive in 2010 | Males alive in 2020 |
|---|---|---|---|---|
| 10–20 | 230 | 180 | 150 | 140 |
| 20–30 | 235 | 205 | 165 | 125 |
| 30–40 | 210 | 160 | 90 | 50 |
| 40–50 | 190 | 100 | 25 | 5 |
| Age group (In 1980) | Females alive in 1990 | Females alive in 2000 | Females alive in 2010 | Females alive in 2020 |
|---|---|---|---|---|
| 10–20 | 240 | 210 | 160 | 100 |
| 20–30 | 225 | 175 | 145 | 105 |
| 30–40 | 190 | 150 | 100 | 60 |
| 40–50 | 220 | 120 | 30 | 18 |
The total number of males between 20 and 30 years of age in 1980 who died in 2000 = 205
The total number of males between 20 and 30 years of age in 1980 who died in 2010 = 165
Thus, the total number of males between 20 and 30 years of age in 1980 who died in the period 2000 to 2010 = 205 - 165 = 40.
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