NTN Data Analytics 2

Question 1

A fire department recorded 450 emergency calls in January, 380 in February, and 520 in March. What is the average number of monthly calls for this quarter?

Accepted Answer

450

Answer

The average is calculated by adding all values and dividing by the number of months: (450 + 380 + 520) / 3 = 1350 / 3 = 450.

Question 2

A dispatcher notices that response times have increased by 15% over the past six months. If the original average response time was 8 minutes, what is the current average?

Accepted Answer

9.2 minutes

Answer

A 15% increase on 8 minutes equals 8 × 0.15 = 1.2 minutes. Adding this to the original: 8 + 1.2 = 9.2 minutes.

Question 3

Which type of chart would be most appropriate for showing the distribution of crime types across different city districts?

Accepted Answer

Stacked bar chart

Answer

A stacked bar chart effectively shows the composition of different categories (crime types) across multiple groups (districts), allowing comparison both within and between districts.

Question 4

A law enforcement agency collected data showing that 60% of traffic accidents occur at intersections, 25% on highways, and the remainder on residential streets. If 840 accidents occurred last year, how many happened on residential streets?

Accepted Answer

126

Answer

Residential streets account for 100% - 60% - 25% = 15% of accidents. 15% of 840 = 840 × 0.15 = 126 accidents.

Question 5

When analyzing a data set of officer performance metrics, the median score is 78 and the mean score is 72. What does this suggest about the distribution of scores?

Accepted Answer

The distribution is skewed to the left (negatively skewed)

Answer

When the mean is lower than the median, the distribution is left-skewed (negatively skewed), indicating some unusually low scores are pulling the mean downward.

NTN - National Testing Network Practice Test

NTN - National Testing Network Practice Test

NTN Data Analytics 2