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Finding the Fourth Proportional to 1,387.67, 1,915.15 and 890.12

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Solution

The fourth proportional to 1,387.67, 1,915.15 and 890.12 is: 1,228.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.67 : 1,915.15 = 890.12 : x
  2. Step 2: Convert to fraction form
    1,387.67/1,915.15 = 890.12/x
  3. Step 3: Cross multiply
    1,387.67x = 1,915.15 × 890.12
  4. Step 4: Simplify right side
    1,387.67x = 1,704,715.88
  5. Step 5: Solve for x
    x = 1,704,715.88/1,387.67
  6. Step 6: Final answer
    x = 1,228.48

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1.5x scale

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.