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Dennis_Churaev [7]
3 years ago
7

Cheryl wants to find the number of hours seventh-graders do homework each week. There are 297 girls and boys in seventh grade. W

hich is the best way for Cheryl to get a representative sample without spending too much time?
A.) She can survey 15 of her friends in the school.
B.) She can survey every sixth-grade student in the school.
C.) She can randomly survey 50 girls in the entire school.
D.) She can randomly survey 50 seventh-graders in the school.
Mathematics
2 answers:
Sveta_85 [38]3 years ago
8 0

Answer:

D

Step-by-step explanation:

Surveying 50 girls would include other grades outside of seventh grade and would not include boys. This would not be a representative sample of the population and would lead to invalid results.

serious [3.7K]3 years ago
7 0
It would be answer D
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Let m be the side length of the fourth smallest possible square with integer value of its area, and let n be the sum of all prim
Natali [406]

Answer:

510

Step-by-step explanation:

It's assumed 0 is not an integer.

M is obviously 2. The area of a square is the square of its side length. If this area must be an integer, then it must be the fourth integer, which is 4. The side length, M=\sqrt{4} = 2

A prime number is a positive integer which can be divided exactly by only itself and 1. In fact, it has only those two factors. The last statement excludes 1 as a prime number. Hence, the prime numbers less than 10 are 2, 3, 5 and 7. Their sum is N=2+3+5+7=17.

To evaluate MN(N-M),

2\times17(17-2)=34\times15=510

6 0
3 years ago
0 A two-inch-long grasshopper can jump a horizontal distance of 40 inches. An athlete, who is _ five feet nine, wants to cover a
Mkey [24]

Answer:

a) nearest jump is JL = 1380 inches = 115ft

b) number of jumps in 1 mile N= 46 jumps

Step-by-step explanation:

Given that the jump length is proportional to the body length.

If 2 inch grasshopper can jump 40 inches.

JL = k(BL)

k = JL/BL

where JL = jump length = 40 inches

BL = Body length = 2 inches.

k = 40/2 = 20

The constant of proportionality is 20.

For the athlete :

BL = 5ft 9 inches = 5(12)+9 = 69 inches.

The jump length of the athlete is:

JL = k(BL) = 20(69)

JL = 1380 inches. = 115ft

The number of jumps in 1 mile is

1 mile = 63360 inches

N = 63360/1380

N = 45.9 = 46

N= 46

Therefore, 46 jumps would be needed.

7 0
3 years ago
Sally works in a cell phone store. She is paid a weekly salary of $80 plus $5.25 for
Viktor [21]

Answer:

First, let's define some variables.

x = # of cell phones sold.

y = total weekly income.

y = $5.25x + $80

a is the correct answer choice.

Step-by-step explanation:

7 0
3 years ago
The day length in Manila, Philippines, varies over time in a periodic way that can be modeled by a trigonometric function.
iris [78.8K]

Answer:

  • L(t) = 727.775 -51.875cos(2π(t +11)/365)
  • 705.93 minutes

Step-by-step explanation:

a) The midline of the function is the average of the peak values:

  (675.85 +779.60)/2 = 727.725 . . . minutes

The amplitude of the function is half the difference of the peak values:

  (779.60 -675.85)/2 = 51.875 . . . minutes

Since the minimum of the function is closest to the origin, we choose to use the negative cosine function as the parent function.

Where t is the number of days from 1 January, we want to shift the graph 11 units to the left, so we will use (t+11) in our function definition.

Since the period is 365 days, we will use (2π/365) as the scale factor for the argument of the cosine function.

Our formula is ...

  L(t) = 727.775 -51.875cos(2π(t +11)/365)

__

b) L(55) ≈ 705.93 minutes

8 0
3 years ago
A local company wants to evaluate their quality of service by surveying their customers.
stich3 [128]

Answer: b. 0.98

Step-by-step explanation:

The formula to find the maximum error of the estimated mean :

E=z^*\dfrac{\sigma}{\sqrt{n}}            (1)

, where \sigma = standard deviation

n= Sample size

z* = Critical z-value.

As per given , we have

\sigma=5

n=100

Critical value for 95% confidence interval = z*=1.96

Put these values in the formula (1), we get

E=(1.96)\dfrac{5}{\sqrt{100}}

E=(1.96)\dfrac{5}{10}=0.98

Hence, the maximum error of the estimated mean quality for a 95% level of confidence is 0.98.

Therefore , the correct answer is b. 0.98 .

6 0
3 years ago
Read 2 more answers
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