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3 years ago

Three times a number plus twice another is 10, while their sum is 10, Find the numbers

1 answer:

5 0

$3a+2b=10 \\\\ a+b=10 \\\\ \boxed{a=10-b} \\\\ 3(10-b)+2b=10 \\\\ 30-3b+b=10 \\\\ -b=10-30 \\\\ -b=-20 \\\\ \boxed{b=20} \\\\ a=10-20 \\\\ \boxed{a=-10}$

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Which function can be used to find the number of cells of bacteria in the population at time t

Nonamiya [84]

Answer:

db / dt = kb

this becomes b(t) = Ce^(kt)

C = 100, the initial population

P(1) = 420 = 100 e^(1k)

4.2 = e^k

ln 4.2 = k

a) thus, b(t) = 100 e^(t ln 4.2)

b) b(3) = 100 e^(3 ln 4.2)

c) growth constant will still be ln 4.2 (constant percentage of populatioin)

d) 10000 = 100 e^(t ln 4.2)

100 = e^(t ln 4.2)

ln 100 = t ln 4.2

t = ln 100 / ln 4.2

Step-by-step explanation:

6 0

2 years ago

-15 + 12x = 5x + 7 -3x SOLVE FOR X

Natali [406]

Answer: $x=\frac{11}{5}$

Simplify both sides of the equation

$-15+12x=5x+7+-3x$

$12x-15=(5x+-3x)+(7)$ (Combine Like Terms)

$12x-15=2x+7$

Subtract 2x from both sides

$12x-15-2x=2x+7-2x\\10x-15=7$

Divide both sides by 10

$\frac{10x}{10} =\frac{22}{10}$

$x=\frac{11}{5}$

6 0

2 years ago

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What are the eletric charges of three subatomic particles

Nata [24]

Answer:

Step-by-step explanation:

as a person who answers in the mathematics session

i will tell you that the answer is 3

7 0

2 years ago

A prticular type of tennis racket comes in a midsize versionand an oversize version. sixty percent of all customers at acertain

svetlana [45]

Answer:

a) P(x≥6)=0.633

b) P(4≤x≤8)=0.8989 (one standard deviation from the mean).

c) P(x≤7)=0.8328

Step-by-step explanation:

a) We can model this a binomial experiment. The probability of success p is the proportion of customers that prefer the oversize version (p=0.60).

The number of trials is n=10, as they select 10 randomly customers.

We have to calculate the probability that at least 6 out of 10 prefer the oversize version.

This can be calculated using the binomial expression:

$P(x\geq6)=\sum_{k=6}^{10}P(k)=P(6)+P(7)+P(8)+P(9)+P(10)\\\\\\P(x=6) = \binom{10}{6} p^{6}q^{4}=210*0.0467*0.0256=0.2508\\\\P(x=7) = \binom{10}{7} p^{7}q^{3}=120*0.028*0.064=0.215\\\\P(x=8) = \binom{10}{8} p^{8}q^{2}=45*0.0168*0.16=0.1209\\\\P(x=9) = \binom{10}{9} p^{9}q^{1}=10*0.0101*0.4=0.0403\\\\P(x=10) = \binom{10}{10} p^{10}q^{0}=1*0.006*1=0.006\\\\\\P(x\geq6)=0.2508+0.215+0.1209+0.0403+0.006=0.633$

b) We first have to calculate the standard deviation from the mean of the binomial distribution. This is expressed as:

$\sigma=\sqrt{np(1-p)}=\sqrt{10*0.6*0.4}=\sqrt{2.4}=1.55$

The mean of this distribution is:

$\mu=np=10*0.6=6$

As this is a discrete distribution, we have to use integer values for the random variable. We will approximate both values for the bound of the interval.

$LL=\mu-\sigma=6-1.55=4.45\approx4\\\\UL=\mu+\sigma=6+1.55=7.55\approx8$

The probability of having between 4 and 8 customers choosing the oversize version is:

$P(4\leq x\leq 8)=\sum_{k=4}^8P(k)=P(4)+P(5)+P(6)+P(7)+P(8)\\\\\\P(x=4) = \binom{10}{4} p^{4}q^{6}=210*0.1296*0.0041=0.1115\\\\P(x=5) = \binom{10}{5} p^{5}q^{5}=252*0.0778*0.0102=0.2007\\\\P(x=6) = \binom{10}{6} p^{6}q^{4}=210*0.0467*0.0256=0.2508\\\\P(x=7) = \binom{10}{7} p^{7}q^{3}=120*0.028*0.064=0.215\\\\P(x=8) = \binom{10}{8} p^{8}q^{2}=45*0.0168*0.16=0.1209\\\\\\P(4\leq x\leq 8)=0.1115+0.2007+0.2508+0.215+0.1209=0.8989$

c. The probability that all of the next ten customers who want this racket can get the version they want from current stock means that at most 7 customers pick the oversize version.

Then, we have to calculate P(x≤7). We will, for simplicity, calculate this probability substracting P(x>7) from 1.

$P(x\leq7)=1-\sum_{k=8}^{10}P(k)=1-(P(8)+P(9)+P(10))\\\\\\P(x=8) = \binom{10}{8} p^{8}q^{2}=45*0.0168*0.16=0.1209\\\\P(x=9) = \binom{10}{9} p^{9}q^{1}=10*0.0101*0.4=0.0403\\\\P(x=10) = \binom{10}{10} p^{10}q^{0}=1*0.006*1=0.006\\\\\\P(x\leq 7)=1-(0.1209+0.0403+0.006)=1-0.1672=0.8328$

7 0

2 years ago

Pls help due at 2:00

slamgirl [31]

Answer:

1. $8.77

2. 498.456

Step-by-step explanation:

4 0

2 years ago

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