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Verdich [7]
3 years ago
15

A girl is now one-third as old as her mother. In three years, she will be two-fifths as old as her mother will be. What are thei

r present ages?
A girl is 9; mom is 27
B girl is 18; mom is 54
C girl is 25; mom is 75
Mathematics
2 answers:
ivanzaharov [21]3 years ago
5 0
<h2>Answer:</h2>

Option: A is the correct answer.

        A girl is 9; mom is 27

<h2>Step-by-step explanation:</h2>

A girl is now one-third as old as her mother.

i.e. if x is the present age of girl.

and y is the present age of her mother.

Then,

x=\dfrac{1}{3}y

i.e.

y=3x-----------(1)

In three years, she will be two-fifths as old as her mother will be.

This means after three years.

The age of girl will be: x+3

and the age of her mother will be: y+3

This means that:

(x+3)=\dfrac{2}{5}\times (y+3)

5(x+3)=2(y+3)\\\\i.e.\\\\5x+15=2y+6

i.e.

5x+15=2\times 3x+6

( since on using equation (1) )

i.e.

5x+15=6x+6\\\\i.e.\\\\6x-5x=15-6\\\\i.e.\\\\x=9

and the value of y from equation (1) is:

y=27

dalvyx [7]3 years ago
3 0
I really want to say A, I mean all of these would fit for the one third of their ages but the two-fifths is kinda tricky. But I am sticking with A.
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4 0
2 years ago
Math help on questions #4 and #5
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<h3>Answer:</h3>

4. -3

5. 3

<h3>Step-by-step explanation:</h3>

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7 0
3 years ago
Silicon wafers are scored and then broken into the many small microchips that will he mounted into circuits. Two breaking method
antoniya [11.8K]

Answer:

a

The estimate is  - 0.0265\le  K \le  0.0465

b

Method B this is because the faulty breaks are less

Step-by-step explanation:

The number of microchips broken in method A is  n_1 = 400

The number of faulty breaks of method A is  X_1 = 32

 The number of microchips broken in method B is  n_2  = 400

 The number of faulty breaks of method A is  X_2 = 32

  The proportion of the faulty breaks to the total breaks in method A is

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The interval of the difference between proportions of improperly broken microchips for the two breaking methods is  

      - 0.0265\le  K \le  0.0465

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