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Finding the Fourth Proportional to 1,428.95, 1,971.74 and 839.68

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Solution

The fourth proportional to 1,428.95, 1,971.74 and 839.68 is: 1,158.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,428.95 : 1,971.74 = 839.68 : x
  2. Step 2: Convert to fraction form
    1,428.95/1,971.74 = 839.68/x
  3. Step 3: Cross multiply
    1,428.95x = 1,971.74 × 839.68
  4. Step 4: Simplify right side
    1,428.95x = 1,655,620.78
  5. Step 5: Solve for x
    x = 1,655,620.78/1,428.95
  6. Step 6: Final answer
    x = 1,158.63

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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.