Home / 123.79-171-100.45

Finding the Fourth Proportional to 123.79, 171 and 100.45

Calculator

Solution

The fourth proportional to 123.79, 171 and 100.45 is: 138.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.79 : 171 = 100.45 : x
  2. Step 2: Convert to fraction form
    123.79/171 = 100.45/x
  3. Step 3: Cross multiply
    123.79x = 171 × 100.45
  4. Step 4: Simplify right side
    123.79x = 17,176.95
  5. Step 5: Solve for x
    x = 17,176.95/123.79
  6. Step 6: Final answer
    x = 138.76

Related Problems

Find fourth proportional to 61.90, 85.50 and 50.23
Half scale
Find fourth proportional to 247.58, 342 and 200.90
Double scale
Find fourth proportional to 124.79, 172.38 and 101.45
Similar ratio
Find fourth proportional to 185.69, 256.50 and 150.68
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.