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Finding the Fourth Proportional to 915.40, 1,371.48 and 427.60

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Solution

The fourth proportional to 915.40, 1,371.48 and 427.60 is: 640.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    915.40 : 1,371.48 = 427.60 : x
  2. Step 2: Convert to fraction form
    915.40/1,371.48 = 427.60/x
  3. Step 3: Cross multiply
    915.40x = 1,371.48 × 427.60
  4. Step 4: Simplify right side
    915.40x = 586,444.85
  5. Step 5: Solve for x
    x = 586,444.85/915.40
  6. Step 6: Final answer
    x = 640.64

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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.