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Finding the Fourth Proportional to 1,428.21, 1,970.67 and 861.06

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Solution

The fourth proportional to 1,428.21, 1,970.67 and 861.06 is: 1,188.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,428.21 : 1,970.67 = 861.06 : x
  2. Step 2: Convert to fraction form
    1,428.21/1,970.67 = 861.06/x
  3. Step 3: Cross multiply
    1,428.21x = 1,970.67 × 861.06
  4. Step 4: Simplify right side
    1,428.21x = 1,696,865.11
  5. Step 5: Solve for x
    x = 1,696,865.11/1,428.21
  6. Step 6: Final answer
    x = 1,188.11

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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.