Question

Josiah kept track of how many songs of each genre were played in an hour from his MP3 player. The counts are displayed in the table below. He has a total of 1,500 songs on his player. Josiah predicted the number of rock songs on his MP3 player to be 300 songs. Which statements about his solution are true? Check all that apply. Josiah’s Music Sample 1 Sample 2 R & B 5 R & B 4 Pop 4 Pop 3 Classical 3 Classical 5 Jazz 2 Jazz 4 Rock 6 Rock 4 Josiah’s work: 10/20 = x/1,500. 10x30/20x30=x/1,500. 300=x He should have found the average of the number of rock songs by averaging 4 and 6 to get 5. He did not multiply the numerator and denominator by the correct number to equal 1,500. His answer will be one-half of what he got because he did not divide 10 by 2 when setting up the proportion. He can only solve the proportion by multiplying the numerator and denominator by a common multiple. He should have multiplied the numerator and denominator by 75, not 30, because 20x75=1,500

Answer 1

Josiah made errors in predicting the number of rock songs on his MP3 player by not averaging the samples correctly and by using the wrong multiplication factor in his proportion calculation. The correct average should be 5, and he should have used a factor of 75 to scale his samples up to the total number of songs.

Step-by-step explanation:

The student has used a proportion to predict the number of rock songs on his MP3 player based on a sample. However, the prediction method has a few mistakes that should be corrected for an accurate estimate.

Josiah's initial prediction did not consider averaging the number of rock songs from both samples, which would have given a better representation of the average occurrence in the sample set. The correct average is (4+6)/2 = 5 rock songs per sample.

The proportion set up by Josiah is 10/20 = x/1,500, which implies that the 10 rock songs in his samples represent half of all songs played. This should have been compared to the total number of songs on the MP3 player, 1,500, requiring him to multiply by a specific number. Yet, the multiplication factor used (30) was incorrect. To scale up 20 to 1,500, he should use the factor of 75, because 20 × 75 = 1,500.

The correct proportion should be 5/20 = x/1,500, which simplifies to 1/4 = x/1,500, and then x = 1,500/4 = 375. Hence, the predicted number of rock songs based on the sample should be 375.

Answer 2

1) He should have found the average of the number of rock songs by averaging 4 and 6 to get 5.

2) He did not multiply the numerator and denominator by the correct number to equal 1,500.

5) He should have multiplied the numerator and denominator by 75, not 30, because 20 x 75 = 1,500.

Step-by-step explanation: