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Finding the Fourth Proportional to 1,390.89, 1,919.45 and 761.45

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Solution

The fourth proportional to 1,390.89, 1,919.45 and 761.45 is: 1,050.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.89 : 1,919.45 = 761.45 : x
  2. Step 2: Convert to fraction form
    1,390.89/1,919.45 = 761.45/x
  3. Step 3: Cross multiply
    1,390.89x = 1,919.45 × 761.45
  4. Step 4: Simplify right side
    1,390.89x = 1,461,564.02
  5. Step 5: Solve for x
    x = 1,461,564.02/1,390.89
  6. Step 6: Final answer
    x = 1,050.81

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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.