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Finding the Fourth Proportional to 1,288.86, 1,931.40 and 640.08

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Solution

The fourth proportional to 1,288.86, 1,931.40 and 640.08 is: 959.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,288.86 : 1,931.40 = 640.08 : x
  2. Step 2: Convert to fraction form
    1,288.86/1,931.40 = 640.08/x
  3. Step 3: Cross multiply
    1,288.86x = 1,931.40 × 640.08
  4. Step 4: Simplify right side
    1,288.86x = 1,236,250.51
  5. Step 5: Solve for x
    x = 1,236,250.51/1,288.86
  6. Step 6: Final answer
    x = 959.18

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.