Home / 1,121.64-1,681.71-428.21

Finding the Fourth Proportional to 1,121.64, 1,681.71 and 428.21

Calculator

Solution

The fourth proportional to 1,121.64, 1,681.71 and 428.21 is: 642.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,121.64 : 1,681.71 = 428.21 : x
  2. Step 2: Convert to fraction form
    1,121.64/1,681.71 = 428.21/x
  3. Step 3: Cross multiply
    1,121.64x = 1,681.71 × 428.21
  4. Step 4: Simplify right side
    1,121.64x = 720,125.04
  5. Step 5: Solve for x
    x = 720,125.04/1,121.64
  6. Step 6: Final answer
    x = 642.03

Related Problems

Find fourth proportional to 560.82, 840.86 and 214.11
Half scale
Find fourth proportional to 2,243.28, 3,363.42 and 856.42
Double scale
Find fourth proportional to 1,122.64, 1,683.21 and 429.21
Similar ratio
Find fourth proportional to 1,682.46, 2,522.57 and 642.32
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.