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Finding the Fourth Proportional to 1,387.29, 1,915.13 and 890.67

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Solution

The fourth proportional to 1,387.29, 1,915.13 and 890.67 is: 1,229.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.29 : 1,915.13 = 890.67 : x
  2. Step 2: Convert to fraction form
    1,387.29/1,915.13 = 890.67/x
  3. Step 3: Cross multiply
    1,387.29x = 1,915.13 × 890.67
  4. Step 4: Simplify right side
    1,387.29x = 1,705,748.84
  5. Step 5: Solve for x
    x = 1,705,748.84/1,387.29
  6. Step 6: Final answer
    x = 1,229.55

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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.