Data and Statistical Interpretation Flashcards

A data set has values: 5, 8, 8, 12, 15, 15, 15, 20. Which measure of central tendency best represents this data?

Answer: Mode

The mode (15) appears most frequently and best describes the most common value in this skewed distribution.

A graph shows company profits over 5 years: $20k, $25k, $18k, $30k, $27k. What was the mean annual profit?

Answer: $24k

Mean = (20+25+18+30+27) ÷ 5 = 120 ÷ 5 = $24k.

A two-way table shows 30 students study French or Spanish in Year 10 or Year 11. 18 study French total, and 16 are in Year 10 total. How many Year 10 students study Spanish if 10 Year 10 students study French?

Answer: 6

Year 10 total = 16; Year 10 French = 10; Year 10 Spanish = 16 − 10 = 6.

The heights of 6 plants (cm) are: 12, 15, 11, 18, 14, 16. What is the median height?

Answer: 14.5 cm

Ordered: 11,12,14,15,16,18; median = average of 3rd and 4th values = (14+15)÷2 = 14.5 cm.

A line graph shows that between March and May, sales dropped from 500 to 350 units. What is the percentage decrease?

Answer: 30%

Decrease = 500 − 350 = 150; percentage = (150/500) × 100 = 30%.

A back-to-back stem-and-leaf plot compares two classes' scores. Class A: 62, 67, 71, 75; Class B: 64, 68, 70, 78. Which class has the higher mean?

Answer: Class B

Class A mean = (62+67+71+75)÷4 = 68.75; Class B mean = (64+68+70+78)÷4 = 70; Class B is higher.

In a histogram, a bar representing the class interval 20–30 has a frequency of 15, and the bar for 30–40 has frequency 25. What fraction of these 40 values falls in the 20–30 interval?

Answer: 3/8

Total = 15 + 25 = 40; fraction for 20–30 = 15/40 = 3/8.