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Finding the Fourth Proportional to 691.65, 1,036.80 and 258.50

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Solution

The fourth proportional to 691.65, 1,036.80 and 258.50 is: 387.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    691.65 : 1,036.80 = 258.50 : x
  2. Step 2: Convert to fraction form
    691.65/1,036.80 = 258.50/x
  3. Step 3: Cross multiply
    691.65x = 1,036.80 × 258.50
  4. Step 4: Simplify right side
    691.65x = 268,015.39
  5. Step 5: Solve for x
    x = 268,015.39/691.65
  6. Step 6: Final answer
    x = 387.50

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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.