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Finding the Fourth Proportional to 1,389.12, 1,916.64 and 864.88

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Solution

The fourth proportional to 1,389.12, 1,916.64 and 864.88 is: 1,193.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.12 : 1,916.64 = 864.88 : x
  2. Step 2: Convert to fraction form
    1,389.12/1,916.64 = 864.88/x
  3. Step 3: Cross multiply
    1,389.12x = 1,916.64 × 864.88
  4. Step 4: Simplify right side
    1,389.12x = 1,657,663.60
  5. Step 5: Solve for x
    x = 1,657,663.60/1,389.12
  6. Step 6: Final answer
    x = 1,193.32

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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.