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Finding the Fourth Proportional to 1,428.60, 1,971.70 and 839.12

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Solution

The fourth proportional to 1,428.60, 1,971.70 and 839.12 is: 1,158.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,428.60 : 1,971.70 = 839.12 : x
  2. Step 2: Convert to fraction form
    1,428.60/1,971.70 = 839.12/x
  3. Step 3: Cross multiply
    1,428.60x = 1,971.70 × 839.12
  4. Step 4: Simplify right side
    1,428.60x = 1,654,492.90
  5. Step 5: Solve for x
    x = 1,654,492.90/1,428.60
  6. Step 6: Final answer
    x = 1,158.12

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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.