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Finding the Fourth Proportional to 890.70, 1,336.19 and 428.40

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Solution

The fourth proportional to 890.70, 1,336.19 and 428.40 is: 642.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    890.70 : 1,336.19 = 428.40 : x
  2. Step 2: Convert to fraction form
    890.70/1,336.19 = 428.40/x
  3. Step 3: Cross multiply
    890.70x = 1,336.19 × 428.40
  4. Step 4: Simplify right side
    890.70x = 572,423.80
  5. Step 5: Solve for x
    x = 572,423.80/890.70
  6. Step 6: Final answer
    x = 642.67

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.