# A consumer group was interested in comparing the operating time of cordless toothbrushes manufactured by two different companies. Group members took a random sample of 18 toothbrushes from Company A and 15 from Company B. Each was charged overnight and the number of hours of use before needing to be recharged was recorded. Company A toothbrushes operated for an average of 119.7 hours with a standard deviation of 1.74 hours; Company B toothbrushes operated for an average of 120.6 hours with a standard deviation of 1.72 hours.1. which of the following statements is true?A. This is a one tailed test of two dependent samplesB. This is a two tailed test of two independent samplesC. This is a one tailed test of two independent samplesD. These samples are matchedE. None of the above

Step-by-step explanation:

The investigation about the operating time of cordless toothbrushes is  in first place associated to two tails experiment since investigation call for evalution of values under and above any given value (mean value). On the other side investigation of two different manufactures implies totally independent samples, unless these two companies have a commercial relationship which is not express in the problem ststement. Therefore the answer is lyrics B

## Related Questions

Which events have a probability of 25 percent? Select three options.choosing a green jelly bean out of a bag that contains 2 green jelly beans, 1 red jelly bean, and 5 yellow jelly beans
rolling a number less than 3 on a six-sided die
spinning a number less than 2 on a spinner that has four equal sections numbered from 1 to 4
choosing an Oregon state quarter out a bag that contains 4 California state quarters, 3 Oregon state quarters, 6 Texas state quarters, and 3 New York state quarters
choosing a spade out of a standard deck of cards that contains 13 hearts, 13 clubs, 13 diamonds, and 13 spades

Choosing a green jelly bean.

Spinning a number less than 2 on a spinner.

Choosing a spade out of a standard deck of cards.

### What are the probabilities?

Probability determines the chances that an event would happen. The probability the event occurs is 1 and the probability that the event does not occur is 0.

Probability of choosing a green jelly bean = number of green jelly bean / total number of beans

2/8 x 100 = 25%

Probability of spinning a number less than 2 on a spinner = number that is less than 2 / total number of sections

1/4 x 100 = 25%

Probability of choosing a choosing a spade= number of spade / total cards in the deck

13/54 x 100 = 25%

The three options that have a probability of 25 percent are:

- Choosing a green jelly bean

- Spinning a number less than 2 on a spinner

- Choosing a spade from a standard deck of cards

The probability of an event occurring is calculated by dividing the number of favorable outcomes by the total number of possible outcomes. A probability of 25 percent corresponds to a ratio of 1 out of 4 (since 25% is one-fourth of 100%). Let's analyze the options:

1. Choosing a green jelly bean: There are 2 green jelly beans out of a total of 2 + 1 + 5 = 8 jelly beans. The probability is 2/8, which simplifies to 1/4 or 25%. This option has a probability of 25%.

2. Rolling a number less than 3 on a six-sided die: There are 2 favorable outcomes (1 and 2) out of 6 possible outcomes (1 through 6). The probability is 2/6, which simplifies to 1/3 or approximately 33.33%. This option does not have a probability of 25%.

3. Spinning a number less than 2 on a spinner: There is 1 favorable outcome (1) out of 4 possible outcomes (1 through 4). The probability is 1/4 or 25%. This option has a probability of 25%.

4. Choosing an Oregon state quarter: There are 3 Oregon state quarters out of a total of 4 + 3 + 6 + 3 = 16 state quarters. The probability is 3/16, which is not equal to 25%.

5. Choosing a spade from a standard deck of cards: There are 13 spades out of a total of 13 + 13 + 13 + 13 = 52 cards. The probability is 13/52, which simplifies to 1/4 or 25%. This option has a probability of 25%.

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Each person plans to take 2 slices of pizza.mark concludes that he would get more pizza by taking 1 slice from each pizza.instead of 2 slices from the first pizza

No if you only get two slices, it doesn't matter which pizza you take it from you still only get 2 slices.

Step-by-step explanation:

H= -16t^2+16t+192 When will the ball hit the​ ground?

t = 4 s

Step-by-step explanation

We can infer the origin from the t⁰ term of the quadratic as being 192 feet above the ground. Initial velocity is  16 ft/s from the t¹ term, gravity is -32 ft/s² from the t² term

0 = -16t² + 16t + 192

0 = -t² + t + 12

0 = t² - t - 12

0 = (t - 4)(t + 3)

so either

t - 4 = 0

t = 4 s

or

t + 3 = 0

t = -3 s  which we ignore as it occurs before the ball is released.

1 is 25% of what number?​

25% of 4 is 1.

Step-by-step explanation:

100% of 4 is 4, therefore 25 percent of 4 equals 1.

What is the premieter of this red polygon

338 in

Step-by-step explanation:

If each of the measures shown is the measure from the vertex to the point of tangency, then that measure contributes twice to the perimeter (once for each leg from the vertex to a point of tangency).

2(22 in + 27 in + 22 in + 98 in) = 2(169 in) = 338 in

Which expression is equivalent to 6(2x+5y)