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xenn [34]
4 years ago
13

On Serena's tenth birthday, her mom was 3 times Serena's age. How old will Serena and her mom be when here mom's age times 0.5 w

ill equal Serena's age? (I think there is a typo in my book. If so, I think this is the question they meant to ask/type. How old will Serena and her mom be when Serena's ages times 0.5 equals her mom's age? Basically, a x 0.5 = b)
Mathematics
1 answer:
charle [14.2K]4 years ago
7 0
So Serena is 10, and her mother is 3 times ten, so her mother is 30. And if we take 30 minus 10 we will have the age of the mom when Serena was born, which is 20. So we know that when Serena is 20, her mother will be 40. So when Serena is 20, she will be half of her mother's age. 40 × 0.5 = 20.
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Mr. Good Wrench advertises that a customer will have to wait no more than 30 minutes for an oil change. A sample of 26 oil chang
Andru [333]

Answer:

The 90% confidence interval for the population standard deviation waiting time for an oil change is (3.9, 6.3).

Step-by-step explanation:

The (1 - <em>α</em>)% confidence interval for the population standard deviation is:

CI=\sqrt{\frac{(n-1)s^{2}}{\chi^{2}_{\alpha/2, (n-1)}}}\leq \sigma\leq \sqrt{\frac{(n-1)s^{2}}{\chi^{2}_{1-\alpha/2, (n-1)}}}

The information provided is:

<em>n</em> = 26

<em>s</em> = 4.8 minutes

Confidence level = 90%

Compute the critical values of Chi-square as follows:

\chi^{2}_{\alpha/2, (n-1)}=\chi^{2}_{0.10/2, (26-1)}=\chi^{2}_{0.05, 25}=37.652

\chi^{2}_{1-\alpha/2, (n-1)}=\chi^{2}_{1-0.10/2, (26-1)}=\chi^{2}_{0.95, 25}=14.611

*Use a Chi-square table.

Compute the 90% confidence interval for the population standard deviation waiting time for an oil change as follows:

CI=\sqrt{\frac{(n-1)s^{2}}{\chi^{2}_{\alpha/2, (n-1)}}}\leq \sigma\leq \sqrt{\frac{(n-1)s^{2}}{\chi^{2}_{1-\alpha/2, (n-1)}}}

     =\sqrt{\frac{(26-1)\times 4.8^{2}}{37.652}}\leq \sigma\leq \sqrt{\frac{(26-1)\times 4.8^{2}}{14.611}}\\\\=3.9113\leq \sigma\leq 6.2787\\\\\approx 3.9 \leq \sigma\leq6.3

Thus, the 90% confidence interval for the population standard deviation waiting time for an oil change is (3.9, 6.3).

3 0
3 years ago
A cone and a cylinder have equal radius, r, and equal altitudes, h. If the slant height of the cone is l, then the ratio of the
77julia77 [94]

Given:

radius of cone = r

height of cone = h

radius of cylinder = r

height of cylinder = h

slant height of cone = l

Solution

The lateral area (A) of a cone can be found using the formula:

A\text{ = }\pi rl

where r is the radius and l is the slant height

The lateral area (A) of a cylinder can be found using the formula:

A\text{ = 2}\pi rh

The ratio of the lateral area of the cone to the lateral area of the cylinder is:

\pi rl\text{ : 2}\pi rh

Canceling out, we have:

\begin{gathered} =\frac{\pi rl}{2\pi rh} \\ =\text{ }\frac{l}{2h}\text{  or l:2h} \end{gathered}

Hence the Answer is option B

3 0
1 year ago
What is the eighth term in the arithmetic sequence defined by the explicit formula an=2n+7?
svetoff [14.1K]
2n+7
2 x 8+8
16+8
24 
24 is the answer 
8 0
3 years ago
Read 2 more answers
A 50 kg ball traveling at 20 m/s would have
kolbaska11 [484]

A : 10000 J

B: 625 J

C: 2500 J

Step-by-step explanation:

Step 1:

We know that ,

Kinetic Energy is given by ((1/2) × m × V²) J

where m = Mass of substance

            V = Velocity

Step 2:

In first case, m= 50 kg, V=20 m/s

Kinetic energy = 0.5 × 50 × 20 ×20

                         =  10000 J

In second case, m= 50 kg, V=20 m/s

Kinetic energy = 0.5 × 50 × 5 ×5

                         =  625 J

In Third case, m= 50 kg, V=10 m/s

Kinetic energy = 0.5 × 50 × 10 ×10

                         =  2500 J

8 0
3 years ago
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Please answer! Help!
svetoff [14.1K]

Answer:

∠F = 42°

Step-by-step explanation:

similar triangles have congruent corresponding angle measures.

so if ΔABC ~ ΔEFG, then ∠B corresponds with ∠F, so ∠F = ∠B

∠F = 42°

4 0
3 years ago
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