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Finding the Fourth Proportional to 1,389.70, 1,916.34 and 1,123.88

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Solution

The fourth proportional to 1,389.70, 1,916.34 and 1,123.88 is: 1,549.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.70 : 1,916.34 = 1,123.88 : x
  2. Step 2: Convert to fraction form
    1,389.70/1,916.34 = 1,123.88/x
  3. Step 3: Cross multiply
    1,389.70x = 1,916.34 × 1,123.88
  4. Step 4: Simplify right side
    1,389.70x = 2,153,736.20
  5. Step 5: Solve for x
    x = 2,153,736.20/1,389.70
  6. Step 6: Final answer
    x = 1,549.78

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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.