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Finding the Fourth Proportional to 430.80, 642.49 and 389.28

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Solution

The fourth proportional to 430.80, 642.49 and 389.28 is: 580.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    430.80 : 642.49 = 389.28 : x
  2. Step 2: Convert to fraction form
    430.80/642.49 = 389.28/x
  3. Step 3: Cross multiply
    430.80x = 642.49 × 389.28
  4. Step 4: Simplify right side
    430.80x = 250,108.51
  5. Step 5: Solve for x
    x = 250,108.51/430.80
  6. Step 6: Final answer
    x = 580.57

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.