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Finding the Fourth Proportional to 1,139.68, 1,572.80 and 891.28

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Solution

The fourth proportional to 1,139.68, 1,572.80 and 891.28 is: 1,230.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,139.68 : 1,572.80 = 891.28 : x
  2. Step 2: Convert to fraction form
    1,139.68/1,572.80 = 891.28/x
  3. Step 3: Cross multiply
    1,139.68x = 1,572.80 × 891.28
  4. Step 4: Simplify right side
    1,139.68x = 1,401,805.18
  5. Step 5: Solve for x
    x = 1,401,805.18/1,139.68
  6. Step 6: Final answer
    x = 1,230.00

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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.