Home / 971.21-1,339.40-639.52

Finding the Fourth Proportional to 971.21, 1,339.40 and 639.52

Calculator

Solution

The fourth proportional to 971.21, 1,339.40 and 639.52 is: 881.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    971.21 : 1,339.40 = 639.52 : x
  2. Step 2: Convert to fraction form
    971.21/1,339.40 = 639.52/x
  3. Step 3: Cross multiply
    971.21x = 1,339.40 × 639.52
  4. Step 4: Simplify right side
    971.21x = 856,563.19
  5. Step 5: Solve for x
    x = 856,563.19/971.21
  6. Step 6: Final answer
    x = 881.95

Related Problems

Find fourth proportional to 485.61, 669.70 and 319.76
Half scale
Find fourth proportional to 1,942.42, 2,678.79 and 1,279.03
Double scale
Find fourth proportional to 972.21, 1,340.77 and 640.52
Similar ratio
Find fourth proportional to 1,456.82, 2,009.09 and 959.27
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.