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Finding the Fourth Proportional to 1,079.91, 1,490.40 and 687.15

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Solution

The fourth proportional to 1,079.91, 1,490.40 and 687.15 is: 948.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,079.91 : 1,490.40 = 687.15 : x
  2. Step 2: Convert to fraction form
    1,079.91/1,490.40 = 687.15/x
  3. Step 3: Cross multiply
    1,079.91x = 1,490.40 × 687.15
  4. Step 4: Simplify right side
    1,079.91x = 1,024,128.36
  5. Step 5: Solve for x
    x = 1,024,128.36/1,079.91
  6. Step 6: Final answer
    x = 948.35

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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.