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Finding the Fourth Proportional to 399.40, 549.54 and 390.19

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Solution

The fourth proportional to 399.40, 549.54 and 390.19 is: 536.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    399.40 : 549.54 = 390.19 : x
  2. Step 2: Convert to fraction form
    399.40/549.54 = 390.19/x
  3. Step 3: Cross multiply
    399.40x = 549.54 × 390.19
  4. Step 4: Simplify right side
    399.40x = 214,425.01
  5. Step 5: Solve for x
    x = 214,425.01/399.40
  6. Step 6: Final answer
    x = 536.87

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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.