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Finding the Fourth Proportional to 690.12, 1,035.64 and 257.28

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Solution

The fourth proportional to 690.12, 1,035.64 and 257.28 is: 386.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    690.12 : 1,035.64 = 257.28 : x
  2. Step 2: Convert to fraction form
    690.12/1,035.64 = 257.28/x
  3. Step 3: Cross multiply
    690.12x = 1,035.64 × 257.28
  4. Step 4: Simplify right side
    690.12x = 266,444.45
  5. Step 5: Solve for x
    x = 266,444.45/690.12
  6. Step 6: Final answer
    x = 386.08

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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.