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Finding the Fourth Proportional to 1,005.35, 1,387.94 and 690.80

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Solution

The fourth proportional to 1,005.35, 1,387.94 and 690.80 is: 953.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,005.35 : 1,387.94 = 690.80 : x
  2. Step 2: Convert to fraction form
    1,005.35/1,387.94 = 690.80/x
  3. Step 3: Cross multiply
    1,005.35x = 1,387.94 × 690.80
  4. Step 4: Simplify right side
    1,005.35x = 958,788.95
  5. Step 5: Solve for x
    x = 958,788.95/1,005.35
  6. Step 6: Final answer
    x = 953.69

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1.5x scale

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.