Number of registered cars in four cities A–D (2017–2020) and their 2020 population (millions).

City	2017	2018	2019	2020	Population (million)
A	7500	8000	9000	9500	0.8
B	1200	1350	1400	1500	0.2
C	6000	7500	8500	10000	0.6
D	5000	6000	6600	7400	0.75

Based on the average growth percentage of registered cars per year during 2017 to 2020 in city A, what will be the estimated number of registered cars in city A in the year 2021?

AAbout 11225

BAbout 10815

CAbout 10415

DAbout 10283 ✓ Correct

Correct answer: (D) About 10283

Explanation

The estimated number of cars in city A in 2021 is about 10283.

The yearly growth percentages in city A are found from each successive pair of years.

From 2017 to 2018 growth is about 6.67 percent, and 2018 to 2019 is 12.5 percent.

From 2019 to 2020 growth is about 5.56 percent.

The average of these three is about 8.24 percent per year.

Applying 8.24 percent growth to 9500 gives about 10283 cars in 2021.

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