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Finding the Fourth Proportional to 710.40, 1,065.60 and 638.40

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Solution

The fourth proportional to 710.40, 1,065.60 and 638.40 is: 957.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    710.40 : 1,065.60 = 638.40 : x
  2. Step 2: Convert to fraction form
    710.40/1,065.60 = 638.40/x
  3. Step 3: Cross multiply
    710.40x = 1,065.60 × 638.40
  4. Step 4: Simplify right side
    710.40x = 680,279.04
  5. Step 5: Solve for x
    x = 680,279.04/710.40
  6. Step 6: Final answer
    x = 957.60

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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.