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2 years ago

16. You found a shortcut to school that saves 5 minutes off of taking the freeway. About 1 in every 10 trips

Mathematics

1 answer:

kykrilka [37]2 years ago

6 0

Answer:

it saves 2.5 minutes

Step-by-step explanation:

The expected value of a random variable is the sum of products of possibilities and the probability of each.

Here, you have a probability of 0.9 of saving 5 minutes, and a probability of 0.1 of adding 20 minutes.

The expected value of the shortcut is ...

0.9(-5) +0.1(20) = -4.5 +2.0 = -2.5

The shortcut is expected to save 2.5 minutes on average.

_____

<em>Additional comment</em>

The probability of 0.9 comes from the 9 of 10 trips that result in a time saving.

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Tan^2 A/1+cot^2 A + cot^2 A/1+tan^2 A=sec^2 A cosec^2 A-3

omeli [17]

$\frac{tan^2x}{1+cot^2x}+\frac{cot^2x}{1+tan^2x}=sec^2x\ cosec^2x-3\\\\L=\frac{tan^2x(1+tan^2x)+cot^2x(1+cot^2x)}{(1+cot^2x)(1+tan^2x)}=\frac{tan^2x+tan^4x+cot^2x+cot^4x}{1+tan^2x+cot^2x+tanxcotx}\\\\=\frac{tan^2x+cot^2x+tan^4x+cot^4x}{1+tan^2x+cot^2x+1}=\frac{tan^2x+2+cot^2x+tan^4x-2+cot^4x}{tan^2x+cot^2x+2}$

$=\frac{(tanx+cotx)^2+(tan^2x-cot^2x)^2}{(tanx+cotx)^2}=\frac{(tanx+cotx)^2}{(tanx+cotx)^2}+\frac{(tan^2x-cot^2x)^2}{(tanx+cotx)^2}\\\\=1+\frac{(tanx-cotx)^2(tanx+cotx)^2}{(tanx+cotx)^2}=1+(tanx-cotx)^2\\\\=1+tan^2x-2tanx\ cotx+cot^2x=tan^2x+cot^2x+1-2\\\\=\left(\frac{sinx}{cosx}\right)^2+\left(\frac{cosx}{sinx}\right)^2-1=\frac{sin^2x}{cos^2x}+\frac{cos^2x}{sin^2x}-1=\frac{sin^4x+cos^4x}{sin^2x\ cos^2x}-1$

$=\frac{(sin^2x)^2+2sin^2x\ cos^2x+(cos^2x)^2-2sin^2x\ cos^2x}{sin^2x\ cos^2x}-1\\\\=\frac{(sin^2x+cos^2x)^2-2sin^2x\ cos^2x}{sin^2x\ cos^2x}-1=\frac{1^2-2sin^2x\ cos^2x}{sin^2x\ cos^2x}-1\\\\=\frac{1}{sin^2x\ cos^2x}-\frac{2sin^2x\ cos^2x}{sin^2x\ cos^2x}-1=\frac{1}{sin^2x}\cdot\frac{1}{cos^2x}-2-1\\\\=cosec^2x\cdot sec^2x-3=sec^2x\ cosec^2x-3=R$

3 0

3 years ago

Solve the following equation:<br> a) 3x - 9 = 27/ 1 - 5x<br> b) 10x - 1/x = 3

mars1129 [50]

Answer:

A) x=9/2 B) x=-1/5, 1/2

Step-by-step explanation:

3x-9=27/1-5x

3x-9=27-5x

3x-(-5x)-9=27

3x+5x-9=27

8x-9=27

8x=27+9

8x=36

x=36/8

simplify

x=9/2

Answer: x=9/2

-----------------------------

10x-1/x=3

(10x^2-1)/x=3

10x^2-1=3*x

10x^2-1=3x

10x^2-3x-1=0

factor out the trinomial,

find two numbers that when they multiply,

you get the third term, which is -1 in this case.

When you add those 2 numbers, you get the second term,

which is -3 in this case.

(5x+1)(2x-1)=0

apply the zero property from here,

set 5x+1=0 and 2x-1=0 and solve for x.

5x=0-1=-1, x=-1/5,

2x=0+1=1, 2x=1, x=1/2.

So x=-1/5, 1/2.

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3 years ago

Please help. 7. 2 × 5. 28

mr_godi [17]

Answer:

The Answer is 10! (I Don't know if you meant 2x5 or 2x5x28) If I am wrong please let me know! If you meant 2x5x28 the answer is 280!

Step-by-step explanation:

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2 years ago

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The amount of time t (in hours) it takes to complete a certain job varies inversely with the number of workers, w. The constant

Vlad [161]

Answer: should be A: 1.75 hours

Step-by-step explanation: divide 28/16 to give you 7/4, then you should turn this into a decimal which gives you 1.75

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4 years ago

A butcher purchases 50 chicks at the rate of Ts.60 per chick.10 of them died and he sold remaining chicks at the rate of Rs.80 p

Romashka-Z-Leto [24]

Answer: 6.25%

Step-by-step explanation:

50 chicks were purchased at Rs. 60. The total cost of the chicks is:

= 50 * 60

= Rs. 3,000

10 of the chicks died which means the farmer was left with 40 chicks.

These chicks are sold at Rs. 80. Total revenue from the sales are:

= 40 chicks * 80

= Rs. 3,200

The profit is:

= 3,200 - 3,000

= Rs. 200

The percentage is:

= Profit / Revenue

= 200 / 3,200

= 6.25%

3 0

3 years ago