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Finding the Fourth Proportional to 1,388.67, 1,916.53 and 891.12

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Solution

The fourth proportional to 1,388.67, 1,916.53 and 891.12 is: 1,229.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,388.67 : 1,916.53 = 891.12 : x
  2. Step 2: Convert to fraction form
    1,388.67/1,916.53 = 891.12/x
  3. Step 3: Cross multiply
    1,388.67x = 1,916.53 × 891.12
  4. Step 4: Simplify right side
    1,388.67x = 1,707,858.21
  5. Step 5: Solve for x
    x = 1,707,858.21/1,388.67
  6. Step 6: Final answer
    x = 1,229.85

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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.