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Hatshy [7]
3 years ago
9

The number A8 is a two-digit number with a digit A and units (ones) digit 8.

Mathematics
1 answer:
loris [4]3 years ago
3 0

Answer:

A = 7

B = 5

C = 2

Step-by-step explanation:

We are given;

A8 × 3B = C730

Now, by inspection, in multiplication of the above, the product of 8 and B must produce a number whose unit digit is 0.

Thus,the only two single digit numbers that can fit this description for B is either 5 or 0 since if they would yield a unit digit of 0 when multiplied by8.

Now, let's test 0.

If B is 0, it means the unit digit of C730 is 0 as wanted while the remaining product of A8 and 3 should yield C73. Now product of A8 and 3 would produce a number with a last digit of 4. But our last digit there in C73 is 3. Thus, it means B cannot be 0 but is 5.

Thus, it means 3B is 35.

Now, we are told that A, B and C could be any single digit number.

from 0 - 9.

Thus, the maximum value of A is 9.

Let's try to put 9 for A and multiply by 35.

If A is 9,then 98 × 35 = 3430

It means that the maximum value of C is 3.

Thus, C can either be 3 or less than 3. So, C is either 1, 2, or 3

Now, if C = 1, it means the C730 is now 1730.

Thus,A8 will be: 1730/35 = 49.43

This is a decimal and thus, it means C ≠ 1.

Now,if C = 2, it means the C730 is now 2730.

Thus,A8 will be: 2730/35 = 78

This is a whole number and thus, it means C = 2

Now,if C = 3, it means the C730 is now 3730.

Thus,A8 will be: 3730/35 = 106.57

This is a decimal and thus, it means C ≠ 3

Thus; A8 is 78 when C = 2

So, A = 7

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3 years ago
Read 2 more answers
A music industry researcher wants to estimate, with a 90% confidence level, the proportion of young urban people (ages 21 to 35
Maslowich

Answer:

1,539

Step-by-step explanation:

Using Simple Random Sampling in an infinite population (this is such a large population that we do not know the exact number) we have that the sample size should be the nearest integer to

\large \frac{Z^2pq}{e^2}

where

<em>Z= the z-score corresponding to the confidence level, in this case 90%, so Z=1.645 (this means that the area under the Normal N(0,1) between [-1.645,1.645] is 90%=0.9) </em>

<em>p= the proportion of young urban people (ages 21 to 35 years) who go to at least 3 concerts a year= 35% = 0.35 </em>

<em>q = 1-p = 0.65 </em>

<em>e = the error proportion = 2% = 0.02 </em>

Making the calculations

\large \frac{Z^2pq}{e^2}=\frac{(1.645)^2*0.35*0.65}{(0.02)^2}=1,539.09

So, the sample size should be 1,539 young urban people (ages 21 to 35 years)

6 0
3 years ago
1:Under what condition will the line px+py+r=0 mat be a normal to the circke x²+y²+2gx+2fy+c=0
ahrayia [7]

Answer:

<h3>#1</h3>

The normal overlaps with the diameter, so it passes through the center.

<u>Let's find the center of the circle:</u>

  • x² + y² + 2gx + 2fy + c = 0
  • (x + g)² + (y + f)² = c + g² + f²

<u>The center is:</u>

  • (-g, -f)

<u>Since the line passes through (-g, -f) the equation of the line becomes:</u>

  • p(-g) + p(-f) + r = 0
  • r = p(g + f)

This is the required condition

<h3>#2</h3>

Rewrite equations and find centers and radius of both circles.

<u>Circle 1</u>

  • x² + y² + 2ax + c² = 0
  • (x + a)² + y² = a² - c²
  • The center is (-a, 0) and radius is √(a² - c²)

<u>Circle 2</u>

  • x² + y² + 2by + c² = 0
  • x² + (y + b)² = b² - c²
  • The center is (0, -b) and radius is √(b² - c²)

<u>The distance between two centers is same as sum of the radius of them:</u>

  • d = √(a² + b²)

<u>Sum of radiuses:</u>

  • √(a² - c²) + √(b² - c²)

<u>Since they are same we have:</u>

  • √(a² + b²) = √(a² - c²) + √(b² - c²)

<u>Square both sides:</u>

  • a² + b² = a² - c² + b² - c² + 2√(a² - c²)(b² - c²)
  • 2c² = 2√(a² - c²)(b² - c²)

<u>Square both sides:</u>

  • c⁴ = (a² - c²)(b² - c²)
  • c⁴ = a²b² - a²c² - b²c² + c⁴
  • a²c² + b²c² = a²b²

<u>Divide both sides by a²b²c²:</u>

  • 1/a² + 1/b² = 1/c²

Proved

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Example:
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   x    represents    100%

rule of three

Price                 Percentage 
+12                         70-
  -x                          100+

x= \frac{12*100}{70} &#10; \\  \\&#10;x= \frac{12*10}{7} &#10; \\  \\ x=17.14




3 0
3 years ago
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