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Finding the Fourth Proportional to 1,018.48, 1,405.80 and 645.28

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Solution

The fourth proportional to 1,018.48, 1,405.80 and 645.28 is: 890.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,018.48 : 1,405.80 = 645.28 : x
  2. Step 2: Convert to fraction form
    1,018.48/1,405.80 = 645.28/x
  3. Step 3: Cross multiply
    1,018.48x = 1,405.80 × 645.28
  4. Step 4: Simplify right side
    1,018.48x = 907,134.62
  5. Step 5: Solve for x
    x = 907,134.62/1,018.48
  6. Step 6: Final answer
    x = 890.67

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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.