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Finding the Fourth Proportional to 499.65, 689.10 and 312.80

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Solution

The fourth proportional to 499.65, 689.10 and 312.80 is: 431.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    499.65 : 689.10 = 312.80 : x
  2. Step 2: Convert to fraction form
    499.65/689.10 = 312.80/x
  3. Step 3: Cross multiply
    499.65x = 689.10 × 312.80
  4. Step 4: Simplify right side
    499.65x = 215,547.03
  5. Step 5: Solve for x
    x = 215,547.03/499.65
  6. Step 6: Final answer
    x = 431.40

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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.