Answer:
Area of shaded part ABCEF = 66 sq.cm
Step-by-step explanation:
AB = 8cm
CD = 8cm
Let DE = x cm
CE = 3x cm
CD = CE + DE = 8cm
x + 3x = 8
4x = 8
x = 8/4 = 2 cm
DE = 2cm
CE = 3 * 2 = 6 cm
Area of triangle ADE = 1/2 * base * height
= 1/2 * DE * AD
= 1/2 * 2 * 11 = 11 sq. cm
Area of triangle AEF = Area of triangle ADE = 11 sq. cm
Area of Rectangle ABCD = l * b = 8 * 11 = 88 sq.cm
Area of shaded part ABCEF = Area of Rectangle ABCD - (Area of triangle AEF + Area of triangle ADE)
= 88 - ( 11 + 11 ) = 88 -22 = 66 sq.cm
We' supposed to indicate which statement is true/false.
Note that, if a sample size is 40 or over, we can use the t distribution even with skewed data. So it's not highly sensitive to non-normality of the population from which samples are taken. So statement A is false.
It's true that the t-distribution assumes that the population from which samples are drawn is normally distributed. So B is true.
For skewed data or with extreme outliers, we can't use the t distribution. We only use t distribution as long as we believe that the population from which samples are drawn is closed to a bell-shape. So C is true.
Lastly, statement D is against statement C. So D is false.
