The sum of 3 numbers is 285. Ratio between 2nd and 3rd numbers is 6 5...
Given:
The sum of 3 numbers is 285. Ratio between 2nd and 3rd numbers is 6 ∶ 5.
Ratio between 1st and 2nd numbers is 3 ∶ 7.
Calculation:
Let the 1st number be x
Let the 2nd number be y
Let the 3rd number be z
The sum of 3rd number is 285
According to the question
Ratio of 2nd and 3rd number
⇒ y : z = 6 : 5
Ratio of 1th and 2nd number
⇒ x : y = 3 : 7
Ratio of x : y : z
⇒ (x × y) : (y × y) : (y × z) = (3 × 6) : (7 × 6) : (7 × 5)
⇒ x : y : z = 18 : 42 : 35
The 3rd number z = 285 × 35 /(18 + 42 + 35)
⇒ z = 285 × 35 / 95 = 105
∴ The 3rd number is 105
The sum of 3 numbers is 285. Ratio between 2nd and 3rd numbers is 6 5...
Understanding the Problem
We have three numbers, and their sum is 285. We also have two ratios that relate these numbers:
1. The ratio of the 2nd to the 3rd number is 6:5.
2. The ratio of the 1st to the 2nd number is 3:7.
Setting Up the Variables
Let's denote the three numbers as:
- 1st number = A
- 2nd number = B
- 3rd number = C
From the ratios, we can express B and C in terms of a variable:
- Since B:C = 6:5, we can express B as 6x and C as 5x for some variable x.
- Since A:B = 3:7, we can express A as (3/7)B = (3/7)(6x) = 18x/7.
Summing Up the Numbers
According to the problem, the sum of the numbers is:
A + B + C = 285
Substituting the values:
(18x/7) + 6x + 5x = 285
To combine these, we need a common denominator:
(b) 18x/7 + (42x/7) + (35x/7) = 285
(b) (18x + 42x + 35x) / 7 = 285
(b) 95x / 7 = 285
Now, multiplying both sides by 7:
(b) 95x = 1995
Now, solving for x:
(b) x = 1995 / 95 = 21
Finding the Values of Each Number
Now we can find each number:
- C = 5x = 5 * 21 = 105
- B = 6x = 6 * 21 = 126
- A = 18x/7 = 18 * 21 / 7 = 54
Conclusion
Thus, the 3rd number, C, is 105, which corresponds to option 'D'.