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Finding the Fourth Proportional to 891.84, 1,228.96 and 642.72

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Solution

The fourth proportional to 891.84, 1,228.96 and 642.72 is: 885.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    891.84 : 1,228.96 = 642.72 : x
  2. Step 2: Convert to fraction form
    891.84/1,228.96 = 642.72/x
  3. Step 3: Cross multiply
    891.84x = 1,228.96 × 642.72
  4. Step 4: Simplify right side
    891.84x = 789,877.17
  5. Step 5: Solve for x
    x = 789,877.17/891.84
  6. Step 6: Final answer
    x = 885.67

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.