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Finding the Fourth Proportional to 1,139.40, 1,571.58 and 918

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Solution

The fourth proportional to 1,139.40, 1,571.58 and 918 is: 1,266.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,139.40 : 1,571.58 = 918 : x
  2. Step 2: Convert to fraction form
    1,139.40/1,571.58 = 918/x
  3. Step 3: Cross multiply
    1,139.40x = 1,571.58 × 918
  4. Step 4: Simplify right side
    1,139.40x = 1,442,710.44
  5. Step 5: Solve for x
    x = 1,442,710.44/1,139.40
  6. Step 6: Final answer
    x = 1,266.20

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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.