2 years ago my mother was 4 times my age then. In 18 years I will be half my mothers new age. How old am I now?

1 answer:

8 0

2 years ago, you were 10 and your Mom was 40. 18 years from now, you will be 12+18 or 30 and your Mom will be 42+18 or 60, so you will be half her age which is 30 years old.

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35. In a simple random sample of 25 high school students, the sample mean of the SAT scores was 1450, and the sample variance wa

Tatiana [17]

Answer:

$1450-2.0\frac{30}{\sqrt{25}}=1450-12$

$1450+2.0\frac{30}{\sqrt{25}}=1450+12$

And the best option would be:

c. 1450 +/- 12

Step-by-step explanation:

Information provided

$\bar X=1450$ represent the sample mean for the SAT scores

$\mu$ population mean (variable of interest)

$s^2 = 900$ represent the sample variance given

n=25 represent the sample size

Solution

The confidence interval for the true mean is given by :

$\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (1)

The sample deviation would be $s=\sqrt{900}= 30$

The degrees of freedom are given by:

$df=n-1=2-25=24$

The Confidence is 0.954 or 95.4%, the value of $\alpha=0.046$ and $\alpha/2 =0.023$ , assuming that we can use the normal distribution in order to find the quantile the critical value would be $z_{\alpha/2} \approx 2.0$