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Finding the Fourth Proportional to 1,538.63, 2,123.31 and 840

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Solution

The fourth proportional to 1,538.63, 2,123.31 and 840 is: 1,159.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,538.63 : 2,123.31 = 840 : x
  2. Step 2: Convert to fraction form
    1,538.63/2,123.31 = 840/x
  3. Step 3: Cross multiply
    1,538.63x = 2,123.31 × 840
  4. Step 4: Simplify right side
    1,538.63x = 1,783,580.40
  5. Step 5: Solve for x
    x = 1,783,580.40/1,538.63
  6. Step 6: Final answer
    x = 1,159.20

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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.