Home / 648.40-972.60-638.80

Finding the Fourth Proportional to 648.40, 972.60 and 638.80

Calculator

Solution

The fourth proportional to 648.40, 972.60 and 638.80 is: 958.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    648.40 : 972.60 = 638.80 : x
  2. Step 2: Convert to fraction form
    648.40/972.60 = 638.80/x
  3. Step 3: Cross multiply
    648.40x = 972.60 × 638.80
  4. Step 4: Simplify right side
    648.40x = 621,296.88
  5. Step 5: Solve for x
    x = 621,296.88/648.40
  6. Step 6: Final answer
    x = 958.20

Related Problems

Find fourth proportional to 324.20, 486.30 and 319.40
Half scale
Find fourth proportional to 1,296.80, 1,945.20 and 1,277.60
Double scale
Find fourth proportional to 649.40, 974.10 and 639.80
Similar ratio
Find fourth proportional to 972.60, 1,458.90 and 958.20
1.5x scale

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.