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Finding the Fourth Proportional to 970.76, 1,339.85 and 639.21

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Solution

The fourth proportional to 970.76, 1,339.85 and 639.21 is: 882.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    970.76 : 1,339.85 = 639.21 : x
  2. Step 2: Convert to fraction form
    970.76/1,339.85 = 639.21/x
  3. Step 3: Cross multiply
    970.76x = 1,339.85 × 639.21
  4. Step 4: Simplify right side
    970.76x = 856,445.52
  5. Step 5: Solve for x
    x = 856,445.52/970.76
  6. Step 6: Final answer
    x = 882.24

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Double scale
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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.