Simple Equation Not So Simple? z = (1.05-1.2)/(0.5/sqrt[100]) = -3.0

[Lindsayk]

Hi All,

My textbook presents the attached problem and solution as a matter of determining z when running a test statistic.

. . . . .\(\displaystyle z\, =\, \dfrac{1.05\, -\, 1.2}{0.5\, \big/\, \sqrt{\strut 100\,}}\, =\, -3.0\)

but when I do the same, seemingly simple problem, I get -0.0075 instead of -3.0?

Anyone know what I am doing wrong?

Many thanks,

Lindsay

 

[Deleted member 4993]

Hi All,

My textbook presents the attached problem and solution as a matter of determining z when running a test statistic.

. . . . .\(\displaystyle z\, =\, \dfrac{1.05\, -\, 1.2}{0.5\, \big/\, \sqrt{\strut 100\,}}\, =\, -3.0\)

but when I do the same, seemingly simple problem, I get -0.0075 instead of -3.0?

Anyone know what I am doing wrong?

Many thanks,

Lindsay

\(\displaystyle z \ = \ \dfrac{1.05-1.2}{\frac{0.5}{\sqrt{100}}}\)

\(\displaystyle z \ = \ \dfrac{-0.15}{0.5} \ * \sqrt{100}\)

\(\displaystyle z \ = \ -0.3\ * 10\)

= ??

 

[Harry_the_cat]

Hi All,

My textbook presents the attached problem and solution as a matter of determining z when running a test statistic.

. . . . .\(\displaystyle z\, =\, \dfrac{1.05\, -\, 1.2}{0.5\, \big/\, \sqrt{\strut 100\,}}\, =\, -3.0\)

but when I do the same, seemingly simple problem, I get -0.0075 instead of -3.0?

Anyone know what I am doing wrong?

Many thanks,

Lindsay

I assume you are using your calculator. Have you got brackets around the numerator and the denominator?

 

[Lindsayk]

\(\displaystyle z \ = \ \dfrac{1.05-1.2}{\frac{0.5}{\sqrt{100}}}\)

\(\displaystyle z \ = \ \dfrac{-0.15}{0.5} \ * \sqrt{100}\)

\(\displaystyle z \ = \ -0.3\ * 10\)

= ??

perfect...huuuuuuuge help! thank you so much!!!! -Lindsay