Class 9 How Quantities Combine: Understanding Data Mock Test (CBSE)

Topics in How Quantities Combine: Understanding Data

• Combining data
• Average of averages
• Weighted mean
• Mixtures and concentration
• Custom weights: rating systems and combined marks
• Visualising and interpreting data
• Stacked bar charts
• 100% stacked bar charts as an alternative to pie charts

How Quantities Combine: Understanding Data practice questions with answers

1. Q1Assertion and reason·1 mark
   Assertion (A): To find the correct combined average of two groups with different sizes, we must use the weighted mean instead of the simple average of their individual averages. Reason (R): The simple average of group averages gives equal weight to each group regardless of its sample size.

   1. (a)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
   2. (b)Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
   3. (c)Assertion (A) is true but Reason (R) is false.
   4. (d)Assertion (A) is false but Reason (R) is true.
   Show answer and step marks

   1. Correct option: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).+1

   Answer: (a)
2. Q2Multiple choice·1 mark
   A student's final score in an academic activity is calculated using weighted components: Written Test (weight $50\%$), Practical (weight $30\%$) and Presentation (weight $20\%$). If the student scores $85$ in the Written Test, $80$ in the Practical and $90$ in the Presentation, what is the student's combined weighted score?

   1. (a)$82.5$
   2. (b)$84.5$
   3. (c)$85.0$
   4. (d)$83.0$
   Show answer and step marks

   1. Correct option: (b) $84.5$+1

   Answer: (b)

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