Question

7. Average of 3 numbers is 87. The 1st number is 4 times the 2nd number and 5 times the 3rd number. What is the first number? A. 99 B. 169 C. 132 D. 180​

Answer 1

Answer:

180

Step-by-step explanation:

Let a b and c are 3 numbers

a+ b + c = 87 *3 = 261

According to question

b= a/4

c = a/5

so a + a/4 + a/5 = 261

solving the equation

(20 a + 5a + 4a)/20= 261

29 a /20 = 261

a = 180

So the 1st number is 180 2nd number is 45 and 3rd number is 36.

Answer 2

Answer:

The correct option is c). 132.

Question : Average of 3 numbers is 87. The 1st number is 4 times the 2nd number and 5 times the 3rd number. What is the first number?

Step-by-step explanation:

From the above question,

They have given :

Let x be the 1st number, y be the 2nd number, and z be the 3rd number.

Since x = 4y and x = 5z, we can set up two equations:

                   4y = 5z

                   x = 4y

We can solve for y and z by dividing the first equation by 4 and dividing the second equation by 5.

                   4y/4 = 5z/4

                   y = 5z/4

                   x/5 = 4y/5

                   z = 4x/5

Now we can substitute the values of y and z into the equation for the average:

                   (x + 5z/4 + 4x/5)/3 = 87

We can simplify the equation and solve for x:

                   3x + 20z/4 = 261

                   3x = 261 - 20z/4

                   3x = 261 - 5z

                   8x = 1053

                   x = 131.625

The 1st number is 131.

We can start by letting x represent the first number, y represent the second number, and z represent the third number. Since the first number is 4 times the second number and 5 times the third number, we can set up two equations: 4y = 5z and x = 4y.

Next, we can solve for y and z by dividing the first equation by 4 and dividing the second equation by 5. This gives us y = 5z/4 and z = 4x/5.

Now we can substitute the values of y and z into the equation for the average: (x + 5z/4 + 4x/5)/3 = 87. We can simplify the equation and solve for x: 3x + 20z/4 = 261. This can be rewritten as 3x = 261 - 20z/4 and 3x = 261 - 5z. We can then divide both sides of the equation by 3 to get 8x = 1053. This gives us x = 131.625.

Therefore, the first number is 131.625.

The correct option is c). 132.

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