Weighted averages and mixtures

Grade 9 Math Worksheet

Circle the best answer.

1. 1.

   Ari mixes 12 L of 15% juice with x L of 45% juice to make a 25% blend. How many liters x of the 45% juice are needed?

   • 18 L
   • 24 L
   • about 2.7 L
   • 6 L
2. 2.

   Pia mixes 12 L of 20% syrup with x L of 70% syrup to make a 30% blend. How many liters x of the 70% syrup are needed?

   • 48 L
   • 3 L
   • 15 L
   • about 1.7 L
3. 3.

   Tala mixes 20 mL of 5% salt water with x mL of 35% salt water to make a 15% blend. How many milliliters x of the 35% water are needed?

   • 10 mL
   • about 5.7 mL
   • 30 mL
   • 40 mL
4. 4.

   Esme needs 30 L of 31% solution from 25% stock and 45% stock. How many liters of the 45% stock?

   • 9 L
   • 9.3 L
   • 21 L
   • 15 L
5. 5.

   Bo needs 12 kg of nut mix worth $5 per kg, made from $4 nuts and $7 nuts. How many kg of the $7 nuts?

   • 4 kg
   • $60
   • 6 kg
   • 8 kg
6. 6.

   Zee needs 40 mL of 18% solution from 10% stock and 30% stock. How many mL of the 30% stock?

   • 20 mL
   • 24 mL
   • 7.2 mL
   • 16 mL
7. 7.

   Current work 60%, final exam 40%. Current work average: 82. Kira wants a final grade of 90. What exam score is needed, and is it possible (scores top out at 100)?

   • Possible: a final score of 98 works.
   • Not possible: the final would need to be 102.
   • Possible: a final score of 95.3 works.
   • Possible: a final score of 40.8 works.
8. 8.

   Current work 70%, final exam 30%. Current work average: 88. Ren wants a final grade of 90. What final exam score is needed, and is it possible (scores top out at 100)?

   • Possible: a final score of 28.4 works.
   • Possible: the final needs to be about 94.7.
   • Possible: a final score of about 90.9 works.
   • Possible: a final score of 92 works.
9. 9.

   Skills 30%, quizzes 30%, final 40%. Skills: 84. Quizzes: 92. Luz wants a final grade of 90. What final score is needed, and is it possible (scores top out at 100)?

   • Possible: a final score of 37.2 works.
   • Possible: the final needs to be 93.
   • Possible: a final score of 94 works.
   • Possible: a final score of 96 works.
10. 10.

    Projects 60%, exam 40%. Projects average: 85. Tala wants a final grade of 92. What exam score is needed, and is it possible (scores top out at 100)?

    • Possible: an exam score of 41 works.
    • Possible: an exam score of about 96.7 works.
    • Not possible: the exam would need to be 102.5.
    • Possible: an exam score of 99 works.