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Finding the Fourth Proportional to 1,305.72, 1,802.40 and 840

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Solution

The fourth proportional to 1,305.72, 1,802.40 and 840 is: 1,159.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,305.72 : 1,802.40 = 840 : x
  2. Step 2: Convert to fraction form
    1,305.72/1,802.40 = 840/x
  3. Step 3: Cross multiply
    1,305.72x = 1,802.40 × 840
  4. Step 4: Simplify right side
    1,305.72x = 1,514,016
  5. Step 5: Solve for x
    x = 1,514,016/1,305.72
  6. Step 6: Final answer
    x = 1,159.53

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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.