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Finding the Fourth Proportional to 1,242.81, 1,862.91 and 420.80

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Solution

The fourth proportional to 1,242.81, 1,862.91 and 420.80 is: 630.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,242.81 : 1,862.91 = 420.80 : x
  2. Step 2: Convert to fraction form
    1,242.81/1,862.91 = 420.80/x
  3. Step 3: Cross multiply
    1,242.81x = 1,862.91 × 420.80
  4. Step 4: Simplify right side
    1,242.81x = 783,903.21
  5. Step 5: Solve for x
    x = 783,903.21/1,242.81
  6. Step 6: Final answer
    x = 630.75

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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.