Barry is 8 years older than his sister. In 3 years, he will be twice as old as she will be then. How old is each now?

Mathematics

1 answer:

Colt1911 [192]3 years ago

7 0

Answer:

Step-by-step explanation:

Present age of Barry = b

Present age of sister = s

Barry is 8 years older than his sister means if we subtract 8 from present age of Barry both will be of equal age

s=b-8 ............(1)

In 3 years means we have to add 3 in their present age

s+3=b+3

then

he will be twice as old as

2(s+3)=(b+3

2s+6=b+3

2s=b+3-6

2s=b-3...............(2)

Put the value of s from (1) to (2), we have

2(b-8)=b-3

2b-16=b-3

2b-b=-3+16

b=13

Put the value of b in (1)

s=13-8

s=5

Present age of Barry = b = 13

Present age of sister = s = 5

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The average systolic blood pressure was found to be 140 mm for people who have high responsibility jobs, specifically investment

defon

Answer:

t = -1.428

Step-by-step explanation:

Average blood pressure among people with high responsibility jobs = u = 140 mm

Number of people sampled for the study = n = 51

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The claim is that practicing yoga decreases the blood pressure. So we have to test that after practicing yoga, the average blood pressure will be lesser than 140. Based on this we can formulate the null and alternate hypothesis as:

Null Hypothesis: $\mu \geq 140$

Alternate Hypothesis: $\mu < 140$

Since population standard deviation is not known, we cannot use z-distribution for this test. We are given the value of sample standard deviation, so t-test will be used for this case.

Test statistic is calculated as:

$t=\frac{x-u}{\frac{s}{\sqrt{n} } }$