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Finding the Fourth Proportional to 690.64, 1,035.96 and 386

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Solution

The fourth proportional to 690.64, 1,035.96 and 386 is: 579

Step by Step Solution

  1. Step 1: Write the proportion equation
    690.64 : 1,035.96 = 386 : x
  2. Step 2: Convert to fraction form
    690.64/1,035.96 = 386/x
  3. Step 3: Cross multiply
    690.64x = 1,035.96 × 386
  4. Step 4: Simplify right side
    690.64x = 399,880.56
  5. Step 5: Solve for x
    x = 399,880.56/690.64
  6. Step 6: Final answer
    x = 579

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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.