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Lynna [10]
2 years ago
13

A chemist needs 30mL of a 12% acid solution for an experiment. The lab has available a 10% solution and a 25% solution. How many

milliliters of the 10% solution and how many milliliters of the 25% solution should the chemist mix to make the 12% solution?
Mathematics
1 answer:
Marat540 [252]2 years ago
6 0

parts of 10% soln, x

parts of 25% soln, y

total soln, x+y =30

{x(0.1) + y(0.25)}/(x + y) = 0.12...eqn 1

x + y = 30...eqn 2

from eqn 2...=》 x = 30-y

subst for x in eqn 1...

=》 {(30-y)(0.1) + y(0.25)}/ 30-y+y = 0.12

=》 (3-.1y+.25y)/30 =0.12

=》 3+.15y = 3.6

=》 .15y = .6

=》 y =4

using x = 30 - y = 26

ans

26ml of 10% soln

4ml of 25% soln

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The brass strip AB has been attached to a fixed support at A and rests on a rough support at B. Knowing that the coefficient of
Andre45 [30]

Answer:

Decrease in temperature = 4.6714°C

Step-by-step explanation:

We know that the formula fro deflection is:

δ = PL/AE + LαΔT

As deflection is equal to zero in this case, the formula becomes

ΔT = -P/αAE   -------------- equation (1)

Now,

we see that only vertical force acting is weight

W = mg = 100*9.81

W = 981N = ∑F_{y}                                  where 1N = 1kgm/s²

Now,

for horizontal forces

As we know that, Sum of all horizontal forces = 0

P - μN = 0

P - μW = 0

P = μW

P = 0.6 * 981

P = 588.8N or 589N

Now we need to calculate the area

area = width * thickness = 20 * 3

area = 60 mm²

Now by substituting all these values in equation 1, wee get

ΔT = -P/αAE = - 588.6/(20*10⁻⁶*60*10⁻⁶*105*10⁹)

ΔT = - 4.6714°C (negative sign indicates decrease)

7 0
2 years ago
The lifespans of lions in a particular zoo are normally distributed. The average lion lives 12.512.512, point, 5 years; the stan
zaharov [31]

This question was not written properly

Complete Question

The lifespans of lions in a particular zoo are normally distributed. The average lion lives 12.5 years; the standard deviation is 2.4 years. Use the empirical rule (68-95-99.7\%)(68−95−99.7%) to estimate the probability of a lion living between 5.3 to 10. 1 years.

Answer:

Thehe probability of a lion living between 5.3 to 10. 1 years is 0.1585

Step-by-step explanation:

The empirical rule formula states that:

1) 68% of data falls within 1 standard deviation from the mean - that means between μ - σ and μ + σ.

2) 95% of data falls within 2 standard deviations from the mean - between μ – 2σ and μ + 2σ.

3) 99.7% of data falls within 3 standard deviations from the mean - between μ - 3σ and μ + 3σ.

Mean is given in the question as: 12.5

Standard deviation : 2.4 years

We start by applying the first rule

1) 68% of data falls within 1 standard deviation from the mean - that means between μ - σ and μ + σ.

μ - σ

12.5 -2.4

= 10.1

We apply the second rule

2) 95% of data falls within 2 standard deviations from the mean - between μ – 2σ and μ + 2σ.

μ – 2σ

12.5 - 2 × 2.4

12.5 - 4.8

= 7.7

We apply the third rule

3)99.7% of data falls within 3 standard deviations from the mean - between μ - 3σ and μ + 3σ.

μ - 3σ

= 12.5 - 3(2.4)

= 12.5 - 7.2

= 5.3

From the above calculation , we can see that

5.3 years corresponds to one side of 99.7%

Hence,

100 - 99.7%/2 = 0.3%/2

= 0.15%

And 10.1 years corresponds to one side of 68%

Hence

100 - 68%/2 = 32%/2 = 16%

So,the percentage of a lion living between 5.3 to 10. 1 years is calculated as 16% - 0.15%

= 15.85%

Therefore, the probability of a lion living between 5.3 to 10. 1 years

is converted to decimal =

= 15.85/ 100

= 0.1585

8 0
2 years ago
Which expression is equivalent to the expression below? StartFraction m + 3 Over m squared minus 16 EndFraction divided by Start
Kamila [148]

Option B: \frac{1}{(m-4)(m-3)} is the correct answer.

Explanation:

The given expression is \frac{(\frac{m+3}{m^2-16}) }{(\frac{m^2-9}{m+4} )}

Simplifying the expression, we have,

\frac{m+3}{m^{2}-16}\times\frac{m+4}{m^2-9}

Factor the equations, m^{2}-16\right and m^{2}-9,we get,

m^{2}-16\right=m^{2}-4^{2}=(m+4)(m-4)

m^{2}-9=m^{2}-3^2=(m+3)(m-3)

Substituting these factored expressions in the above expression, we have,

\frac{m+3}{(m+4)(m-4)}\times\frac{m+4}{(m+3)(m-3)}

Cancelling the common terms m+3 and m+4 , we get,

\frac{1}{(m-4)(m-3)}

Thus, the expression equivalent to \frac{(\frac{m+3}{m^2-16}) }{(\frac{m^2-9}{m+4} )} is \frac{1}{(m-4)(m-3)}

Hence, Option B is the correct answer.

3 0
2 years ago
Read 2 more answers
Bella has joined a new gym in town. The cost of membership is $25 per month. The after-hours policy at the gym allows her to wor
hjlf

The total monthly bill of the gym = $53

The cost of membership of a month = $25

Let 'n' be extra the number of hours Bella worked on.

The cost for working on extra hours = $4

So, we have to determine the equation, Bella worked out after hours.

We will determine the equation by:

(Monthly cost of membership) + ( cost for extra hours \times number of hours extra worked on )  = Total monthly bill received

So, we get

\$25+(4 \times n) = \$53

$25+4n = $53 is the required equation.

Therefore, $25+4n = $53  equation can be used to determine how many times Bella worked out after hours.

4 0
2 years ago
In a circle with center C and radius 6, minor arc AB has a length of 4pi. What is the measure, in radians, of central angle ACB?
valina [46]
To solve this problem, we need to know that 
arc length = r θ  where θ is the central angle in radians.

We're given
r = 6 (units)
length of minor arc AB = 4pi
so we need to calculate the central angle, θ
Rearrange equation at the beginning,
θ = (arc length) / r = 4pi / 6 = 2pi /3

Answer: the central angle is 2pi/3 radians, or (2pi/3)*(180/pi) degrees = 120 degrees
8 0
2 years ago
Read 2 more answers
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