Question

Does delaying oral practice hinder learning a foreign language?
Researchers randomly assigned 25 beginning students of Russian to
begin speaking practice immediately and another 25 to delay
speaking for 4 weeks. At the end of the semester both groups took a
standard test of comprehension of spoken Russian. Suppose that in
the population of all beginning students, the test scores for early
speaking vary according to the *N*(30, 8) distribution and
scores for delayed speaking have the *N*(27, 4)
distribution.

(a) What is the sampling distribution of the mean score
*x* in the early speaking group in many repetitions of the
experiment? (Round your answers for *s* to two decimal
places.)

Mean | = |

s |
= |

What is the sampling distribution of the mean score *y* in
the delayed speaking group?

Mean | = |

s |
= |

(b) If the experiment were repeated many times, what would be the
sampling distribution of the difference *y* - *x*
between the mean scores in the two groups? (Round your answer for
*s* to two decimal places.)

Mean | = |

s |
= |

(c) What is the probability that the experiment will find
(misleadingly) that the mean score for delayed speaking is at least
as large as that for early speaking? (Round your answer to four
decimal places.)

Answer #1

Does delaying oral practice hinder learning a foreign language?
Researchers randomly assigned 25 beginning students of Russian to
begin speaking practice immediately and another 25 to delay
speaking for 4 weeks. At the end of the semester both groups took a
standard test of comprehension of spoken Russian. Suppose that in
the population of all beginning students, the test scores for early
speaking vary according to the N(27, 4) distribution and scores for
delayed speaking have the N(21, 8) distribution....

Does delaying oral practice hinder learning a foreign language?
Researchers randomly assigned 16 beginning students of Russian to
begin speaking practice immediately and another 16 to delay
speaking for 4 weeks. At the end of the semester both groups took a
standard test of comprehension of spoken Russian. Suppose that in
the population of all beginning students, the test scores for early
speaking vary according to the N(34, 8) distribution and
scores for delayed speaking have the N(29, 6)
distribution....

Does delaying oral practice hinder learning a foreign language?
Researchers randomly assigned 27 beginning students of Russian to
begin speaking practice immediately and another 27 to delay
speaking for 4 weeks. At the end of the semester both groups took a
standard test of comprehension of spoken Russian. Suppose that in
the population of all beginning students, the test scores for early
speaking vary according to the N(34, 9) distribution and scores for
delayed speaking have the N(29, 4) distribution....

Does delaying oral practice hinder learning a foreign language?
Researchers randomly assigned 28 beginning students of Russian to
begin speaking practice immediately and another 28 to delay
speaking for 4 weeks. At the end of the semester both groups took a
standard test of comprehension of spoken Russian. Suppose that in
the population of all beginning students, the test scores for early
speaking vary according to the N(34, 6) distribution and scores for
delayed speaking have the N(33, 6) distribution....

Does delaying oral practice hinder learning a foreign language?
Researchers randomly assigned 16 beginning students of Russian to
begin speaking practice immediately and another 16 to delay
speaking for 4 weeks. At the end of the semester both groups took a
standard test of comprehension of spoken Russian. Suppose that in
the population of all beginning students, the test scores for early
speaking vary according to the N(31, 7) distribution and
scores for delayed speaking have the N(27, 8)
distribution....

In the journal Mental Retardation, an article reported the
results of a peer tutoring program to help mildly mentally retarded
children learn to read. In the experiment, the mildly retarded
children were randomly divided into two groups: the experimental
group received peer tutoring along with regular instruction, and
the control group received regular instruction with no peer
tutoring. There were n1 = n2 = 36 children in each group. The
Gates-MacGintie Reading Test was given to both groups before
instruction...

In the journal Mental Retardation, an article reported
the results of a peer tutoring program to help mildly mentally
retarded children learn to read. In the experiment, the mildly
retarded children were randomly divided into two groups: the
experimental group received peer tutoring along with regular
instruction, and the control group received regular instruction
with no peer tutoring. There were n1 =
n2 = 30 children in each group. The
Gates-MacGintie Reading Test was given to both groups before
instruction...

In the journal Mental Retardation, an article reported
the results of a peer tutoring program to help mildly mentally
retarded children learn to read. In the experiment, the mildly
retarded children were randomly divided into two groups: the
experimental group received peer tutoring along with regular
instruction, and the control group received regular instruction
with no peer tutoring. There were n1 =
n2 = 30 children in each group. The
Gates-MacGintie Reading Test was given to both groups before
instruction...

Why do we naturally tend to trust some strangers more than
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between eye color and trustworthiness. In their experiment the
researchers took photographs of 80 students (20 males with brown
eyes, 20 males with blue eyes, 20 females with brown eyes, and 20
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Why do we naturally tend to trust some strangers more than
others? One group of researchers decided to study the relationship
between eye color and trustworthiness. In their experiment the
researchers took photographs of 80 students (20 males with brown
eyes, 20 males with blue eyes, 20 females with brown eyes, and 20
females with blue eyes), each seated in front of a white background
looking directly at the camera with a neutral expression. These
photos were cropped so the...

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