ElectricPavlov

10 pounds is BELOW the mean     11.6 - 10 = 1.6     1.6/1.3 = 1.231 standard deviations below the mean

Look at your negative z -score table 1.23  corresponds to the fraction .1093

  ....this is how many books weigh LESS than 10 pounds....the remainder   (1-.1093) will weigh MORE than 10 pounds

(1-.1093)(136) = ~~ 121 books weigh more than 10#

(Thanx CHris for spotting my typo!)

One standard deviation above and below the mean encompasses 68%

68% x 97=~~66

When I was in school, we were taught to remember the standard bell curve values like the one below:

First one : False

Second one    g(x) max is 5   f(x) max is 2

Third one :    g(x) x-intercept s   -2 and 2     f(x) x-intercepts  -2 and 2

Fourth one:   g(x)  y intercept (where x=0) is -4     f(x) where x= 0 is 2

-2 cos^2 = -1     divide both sides of the equation by  -2

cos^2 = 1/2

cos = +- sqrt 2 / 2          pi/4   3 pi/4    5pi/4      7 pi/4

Value at 0  = 1

Value at 2 =~~4

(1-4)/(0-2) = 3/2 = 1  1/2

A negative z-score is BELOW the mean

3.9 -1.7 x 1.2 =  1.86 yrs

(12+4-1) x 5 =75

5280 ft / 1 mi  =  4488 ft/x mi

x=4488/5280 mi = .85 miles

-2(-8.4) + y - k  = .5(-8.4)+y -14

16.8 - k = -4.2 -14

k =35

No problem for me......but I am a registered user.....I will try it a s a 'guest' to see if it happens.....

Nope....works when I am a 'guest' too     .... make sure your cursor is not on the home button when you are using the calc....dunno.