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Finding the Fourth Proportional to 1,289.70, 1,779.12 and 816.80

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Solution

The fourth proportional to 1,289.70, 1,779.12 and 816.80 is: 1,126.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,289.70 : 1,779.12 = 816.80 : x
  2. Step 2: Convert to fraction form
    1,289.70/1,779.12 = 816.80/x
  3. Step 3: Cross multiply
    1,289.70x = 1,779.12 × 816.80
  4. Step 4: Simplify right side
    1,289.70x = 1,453,185.22
  5. Step 5: Solve for x
    x = 1,453,185.22/1,289.70
  6. Step 6: Final answer
    x = 1,126.76

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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.