According to the chart below, which sets of IQ scores fall in the bottom 50th percent of frequency?

(65 - 69), (130 - 144), (115 - 129), (70 - 84)

Explanation:

The bottom 50th percentile means could be reffered to as the lower bound of the median.

Writing out the IQ scores and its frequency

IQ score

Frequency

(65-69)(70-84)(85-99)(100-114)(115-129)(130 -144)

- - 2 - - - 15 - - - - 34 - - - 36 - - - - 10 - - - - - 3

Rearranging the frequency

2, 3, 10, 15, 34, 36

Cummulative frequency = 2, 5, 15, 30, 64, 100

50% of frequency = 50/100 × total Cummulative frequency

0.5 × 100 = 50

Therefore IQ scores below the 50 Cummulative frequency point are the IQ's with frequency 2, 3, 10 and 15

The corresponding IQ scores are;

(65 - 69), (130 - 144), (115 - 129), (70 - 84)