With n tosses, there are a total of 2^n possible outcomes. We need 15 of theses to be heads.
Since the tosses are random, we want to count the ways to have exactly 15 of them being heads. That will be C(n,15) ways to pick which tosses are heads.
The probability will be given by:
C(n,15)/2^n=0.0148
At this point we use various values of n until we get the correct probability.
n=18⇒0.003112793
n=19⇒0.007392883
n=20⇒0.014785767
n=21⇒0.025875092
Answer:
n=20
She receives 21. 1/5 of 30 is 6, or the number of picture messages Lilly receives. 7/8 of 24, the number of remaining messages, is equal to 21.
Answer:
the third one
Step-by-step explanation:
........
Answer:
I think it is 441
Step by step explanation:
To make a rectangle you need to pick any two of the vertical lines, and any two of the horizontal lines. So there would be 91 squares and 441 rectangles.
Simplify:
(7/9)/(3/5)
Multiply the numerator by the reciprocal of the denominator, (7/9)/(3/5) = 7/9×5/3:
(7×5)/(9×3)
9×3 = 27:
(7×5)/27
7×5 = 35:
Answer: 35/27
