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Finding the Fourth Proportional to 1,085.64, 1,498.40 and 643.78

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Solution

The fourth proportional to 1,085.64, 1,498.40 and 643.78 is: 888.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,085.64 : 1,498.40 = 643.78 : x
  2. Step 2: Convert to fraction form
    1,085.64/1,498.40 = 643.78/x
  3. Step 3: Cross multiply
    1,085.64x = 1,498.40 × 643.78
  4. Step 4: Simplify right side
    1,085.64x = 964,639.95
  5. Step 5: Solve for x
    x = 964,639.95/1,085.64
  6. Step 6: Final answer
    x = 888.54

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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.