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2 years ago

Simplify to create an equivalent expression. −3(2+4k)+7(2k−1)

Mathematics

2 answers:

Genrish500 [490]2 years ago

7 0

Answer:

$\huge\boxed{2k-13}$

Step-by-step explanation:

$\sf -3(2+4k)+7(2k-1)\\Expanding \ brackets\\-6-12k+14k-7\\Combining \ like \ terms\\-12k+14k-6-7\\2k -13$

prisoha [69]2 years ago

6 0

2k-13
First step= -3(2+4K)+7(2k-1)
Second step= -6 - (12k) + 14k- 7
Third step= -12k+14k - 6 -7= 2k-13

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The heights of men in a certain population follow a normal distribution with mean 69.7 inches and standard deviation 2.8 inches.

Mama L [17]

Answer:

a) P(Y > 76) = 0.0122

b) i) P(both of them will be more than 76 inches tall) = 0.00015

ii) P(Y > 76) = 0.0007

Step-by-step explanation:

Given - The heights of men in a certain population follow a normal distribution with mean 69.7 inches and standard deviation 2.8 inches.

To find - (a) If a man is chosen at random from the population, find

the probability that he will be more than 76 inches tall.

(b) If two men are chosen at random from the population, find

the probability that

(i) both of them will be more than 76 inches tall;

(ii) their mean height will be more than 76 inches.

Proof -

P(Y > 76) = P(Y - mean > 76 - mean)

= P( $\frac{( Y- mean)}{S.D}$ ) > $\frac{( 76- mean)}{S.D}$ )

= P(Z > $\frac{( 76- mean)}{S.D}$ )

= P(Z > $\frac{76 - 69.7}{2.8}$ )

= P(Z > 2.25)

= 1 - P(Z ≤ 2.25)

= 0.0122

⇒P(Y > 76) = 0.0122

(i)

P(both of them will be more than 76 inches tall) = (0.0122)²

= 0.00015

⇒P(both of them will be more than 76 inches tall) = 0.00015

(ii)

Given that,

Mean = 69.7,

$\frac{S.D}{\sqrt{N} }$ = 1.979899,

Now,

P(Y > 76) = P(Y - mean > 76 - mean)

= P( $\frac{( Y- mean)}{\frac{S.D}{\sqrt{N} } }$ )) > $\frac{( 76- mean)}{\frac{S.D}{\sqrt{N} } }$ )

= P(Z > $\frac{( 76- mean)}{\frac{S.D}{\sqrt{N} } }$ )

= P(Z > $\frac{( 76- 69.7)}{1.979899 }$ ))

= P(Z > 3.182)

= 1 - P(Z ≤ 3.182)

= 0.0007

⇒P(Y > 76) = 0.0007

6 0

3 years ago

Ms. Lorahs smartphone has 3.5 GB of free storage space, which is 27.5% of the total storage space on her smartphone. What is the

statuscvo [17]

12.73 GB total when rounded to the nearest 100th.

3.5/27.5=y

y•100= 12.73

4 0

3 years ago

Three rats in a lab are injected a type of medicine. The independent probabilities for each rat exhibiting side effects are 0.5,

EleoNora [17]

Step-by-step explanation:

There are four possible values of X: 0 rats show side effects, 1 rat shows side effects, 2 rats show side effects, or all 3 rats show side effects.

Probability X = 0:

P = (1 − 0.5) (1 − 0.4) (1 − 0.3)

P = 0.21

Probability X = 1:

P = (0.5) (1 − 0.4) (1 − 0.3) + (1 − 0.5) (0.4) (1 − 0.3) + (1 − 0.5) (1 − 0.4) (0.3)

P = 0.44

Probability X = 2:

P = (0.5) (0.4) (1 − 0.3) + (0.5) (1 − 0.4) (0.3) + (1 − 0.5) (0.4) (0.3)

P = 0.29

Probability X = 3:

P = (0.5) (0.4) (0.3)

P = 0.06

7 0

3 years ago

Situation:

Gala2k [10]

Answer:

5.5 days (nearest tenth)

Step-by-step explanation:

<u>Given formula:</u>

$\sf N=N_0e^{-kt}$

$\sf N_0$ = initial mass (at time t=0)
N = mass (at time t)
k = a positive constant
t = time (in days)

Given values:

$\sf N_0$ = 11 g
k = 0.125

Half-life: The <u>time</u> required for a quantity to reduce to <u>half of its initial value</u>.

To find the time it takes (in days) for the substance to reduce to half of its initial value, substitute the given values into the formula and set N to half of the initial mass, then solve for t:

$\begin{aligned}\sf N & = \sf N_0e^{-kt}\\\\\implies \sf \dfrac{11}{2} & = \sf 11e^{-0.125t}\\\\\sf \dfrac{1}{2} & = \sf e^{-0.125t}\\\\\sf \ln \left(\dfrac{1}{2}\right) & = \sf \ln e^{-0.125t\\\\\sf \ln \left(\dfrac{1}{2}\right) & = \sf -0.125t \ln e\\\\\sf \ln \left(\dfrac{1}{2}\right) & = \sf -0.125t(1)\\\sf t & = \sf \dfrac{\ln \left(\dfrac{1}{2}\right)}{-0.125}\\\\\sf t & = \sf 5.545177444...\\\\\sf t & = \sf 5.5\:\:days\:\:(nearest\:tenth)\end{aligned}$