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kap26 [50]
4 years ago
14

Dr. Park is interested in how the functioning of the brain changes with age and how this, in turn, affects older individuals’ me

mory abilities. She randomly selects 11 older and 16 younger adults to study pictures of landscapes presented for 5 seconds each. After a 10-minute rest period, both groups perform a visual recognition test. They view a series of pictures and categorize each as either "old" (part of the set they studied) or "new" pictures. While this test is occurring, researchers use fMRI to measure the participants’ brain activity. Dr. Park and her team notice that the older adults all produced similar amounts of activity during the task. The younger adults, on the other hand, showed much more diversity of brain activity. Some younger study participants had a large amount of activity, while others had much less. Would it be valid for Dr. Park to use the independent-measures t test to test whether the brain activity of younger adults is different from that of older adults during a visual recognition task?
a. Yes, because none of the assumptions of the independent-measures t test are violated.
b. Yes, because the independent-measures t test is a robust test. No, because the two groups studied are not independent.
c. No, because the two populations from which the samples are selected do not appear to have equal variances.
Mathematics
2 answers:
a_sh-v [17]4 years ago
8 0

Answer:

Option C.  No, because the two populations from which the samples are selected do not appear to have equal variances.

Step-by-step explanation:

The variance measures how far a set of (random) numbers are spread out from their average value.

The fact that the younger adults show diversity in their brain activity while the older adults produce similar activities show that there are no equal variances in the two populations from which the samples are selected.

Therefore it would not be valid for Dr. Park to use the independent-measures t-test to test whether the brain activity of younger adults is different from that of older adults during a visual recognition task

AnnZ [28]4 years ago
5 0

Answer:

No, because the two populations from which the samples are selected do not appear to have equal variances.

Step-by-step explanation:

We know that in the given study the two groups studied are older and younger people. The samples are randomly selected and are independent of each other. The t-test is a robust test if the assumptions are followed. In the given study, we are given that the older adults produced a similar response, while the younger adults produced more of diverse brain activity. Therefore, the variance of younger adults would not be equal to the variance of older adults. Since one of the assumptions of the t-test is that the population of the two groups have same variance and here this assumption appears to be violated. Hence the correct option is:  No, because the two populations from which the samples are selected do not appear to have equal variances.

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4. Simplify the expression
FromTheMoon [43]

Answer:

C. 2x + 12

Step-by-step explanation:

2(10) + 2(x-4)

= 20 + 2x - 8

= 2x + 20 - 8

= 2x + 12

7 0
3 years ago
The area of a rectangular wall of a barn is 85 square feet. Its length is 12 feet longer than the width. Find the length and wid
MaRussiya [10]

Answer:

Length = 17 feet, Width = 5 feet

Step-by-step explanation:

Given:

The area of a rectangular wall of a barn is 85 square feet.

Its length is 12 feet longer than the width.

Question asked:

Find the length and width of the wall of the barn.

Solution:

Let width of a rectangular wall of a barn = x

<u>As length is 12 feet longer than the width.</u>

Length of a rectangular wall of a barn = 12+x

As we know:

Area\ of\ rectangle=length\times breadth

85=(12+x)x\\\\85=12x+x^{2} \\

Subtracting both sides by 85

x^{2} +12x-85=0\\x^{2} +17x-5x-85=0\\Taking\ common\\x+(x+17)-5x(x+17)=0\\(x+17)(x-5)=0\\x+17=0, x-5=0\\x=-17,x=5

As width can never be in negative, hence  width of a rectangular wall of a barn = x = 5 feet

Length of a rectangular wall of a barn = 12+x=12+5=17\ feet

Therefore, length and width of the wall of the barn is 17 feet and 5 feet respectively.

                 

4 0
4 years ago
The distance between capeton &amp; Jonesville is 80 miles. The scale on the map is 0.75 in 10 Mi how far part are the cities on
ikadub [295]

Answer:

6 in = 80 miles

Step-by-step explanation:

Given that:

Distance between Capeton and Jonesville = 80 miles.

Map scale : 0.75 in = 10 miles ; this means 0.75 inches on the map represents 10 miles on land.

Hence, If ;

0.75 inches = 10 miles

x inches = 80 miles

Cross multiply :

10 * x = 80 * 0.75

10x = 60

10x / 10 = 60 / 10

x = 6 inches

Hence,

6 in = 80 miles

4 0
3 years ago
The length of a rectangle is four times its width.
Irina-Kira [14]

Answer:

Length = 24 yd

Width = 6 yd

Step-by-step explanation:

To start out, we can begin by saying that "l" is the length of the rectangle, and "w" is the width.

Since we know that the length (l) is 4 times its width we can say that 4 times the width is equal to its length. We would write this out this way :

4w = l

Next, we know that the perimeter is 60yd (as it is given in the question). We also know that the perimeter of a rectangle is all of its sides, added. Meaning the length plus the length, plus the width and the width. So, we can use the equation :

2l + 2w = p

"p" being the perimeter. And, since the perimeter is 60, we can place in 60 for "p"

2l + 2w = 60

Now we can use this information to combine the terms, and find the width and length. We first do this by noticing that in the first equation, it shows that "l" (the length) is equal to 4w. This means that we can put 4w in place of the "l" in the second equation. We can do this, becuase we know that "l" is equal to 4w. (from the first eqaution)

2 (4w) + 2w = 60

Now, we solve

2 * 4w = 8w

8w + 2w = 10w

So now we have :

10w = 60

To get the width, all we have to do is simply get "w" alone. We can do this by dividing both sides by 10.

10w = 60

/10     /10

w = 6

Therefore, the width is 6.

Now, going back to the first equaiton, we already know that the length is 4 times the width, meaning all we have to do is multiply 6 by 4 to get the length.

6 * 4 = 24.

Therefore, the length is 24.

Lastly, to check and make sure we are correct, we can go back to the second equation. 2l + 2w = 60

2 (24) + 2 (6) = 60

2 * 24 = 48

2 * 6 = 12

48 + 12 = 60

60 = 60

Now, we officially know that the length of the rectangle is 24 and the width is 6.

6 0
2 years ago
8x(5+7). please answer will give 10 pts &amp; brainiest
Veseljchak [2.6K]

Answer:

96

Step-by-step explanation:

8x(5+7)

Parentheses first

8* (12)

Then multiply

96

8 0
3 years ago
Read 2 more answers
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