Log inSign up free

Question Bank / Math / One-Variable Data

One-variable data: Distributions and measures of center and spread SAT question

Math · Problem-Solving and Data Analysis · Hard · Answer it here, explanation included.

 Masses (kilograms)
Andrew2.42.53.63.12.52.7
Mariax3.12.72.93.32.8
 

Andrew and Maria each collected six rocks, and the masses of the rocks are shown in the table above. The mean of the masses of the rocks Maria collected is 0.1 kilogram greater than the mean of the masses of the rocks Andrew collected. What is the value of x ?

Enter a number or fraction (like 3/17 or 0.176). Press Enter to check.

ExplanationShow

The correct answer is 2.6. Since the mean of a set of numbers can be found by adding the numbers together and dividing by how many numbers there are in the set, the mean mass, in kilograms, of the rocks Andrew collected is the fraction with numerator 2 point 4, plus 2 point 5, plus 3 point 6, plus 3 point 1, plus 2 point 5, plus 2 point 7, and denominator 6, equals 16 point 8 over 6., or 2.8. Since the mean mass of the rocks Maria collected is 0.1 kilogram greater than the mean mass of rocks Andrew collected, the mean mass of the rocks Maria collected is 2 point 8, plus 0 point 1, equals 2 point 9 kilograms. The value of x can be found by writing an equation for finding the mean: the fraction with numerator x plus 3 point 1, plus 2 point 7, plus 2 point 9, plus 3 point 3, plus 2 point 8, and denominator 6, equals 2 point 9. Solving this equation gives x equals 2 point 6. Note that 2.6 and 13/5 are examples of ways to enter a correct answer.

 

 

Drill this skill on Aceit

Adaptive practice, a daily plan, and score tracking take a free account so we can save your work.

Practice this skill

More One-variable data: Distributions and measures of center and spread questions