Home / 430.38-640.39-428.94

Finding the Fourth Proportional to 430.38, 640.39 and 428.94

Calculator

Solution

The fourth proportional to 430.38, 640.39 and 428.94 is: 638.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    430.38 : 640.39 = 428.94 : x
  2. Step 2: Convert to fraction form
    430.38/640.39 = 428.94/x
  3. Step 3: Cross multiply
    430.38x = 640.39 × 428.94
  4. Step 4: Simplify right side
    430.38x = 274,688.89
  5. Step 5: Solve for x
    x = 274,688.89/430.38
  6. Step 6: Final answer
    x = 638.25

Related Problems

Find fourth proportional to 215.19, 320.20 and 214.47
Half scale
Find fourth proportional to 860.76, 1,280.78 and 857.88
Double scale
Find fourth proportional to 431.38, 641.88 and 429.94
Similar ratio
Find fourth proportional to 645.57, 960.59 and 643.41
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.