Given: x + y = 10.<br><br> If x = -21, what is y?

Peppermint Patty is very discouraged about her chances on a 10-item true-false quiz. If she randomly answers each question, what

Alona [7]

We can solve this problem using the binomial probability equation:

P = [n! / (n – r)! r!] p^r q^(n – r)

where the variables are:

n = total number of questions = 10

r = number of correct = at least 5

p = probability of success = 0.5

q = probability of failure = 0.5

So what we have to do is to calculate for P for r = 5 to 10

when r = 5

P = [10! / (10 – 5)! 5!] 0.5^5 0.5^(10 – 5)

P = 0.246

when r = 6

P = [10! / (10 – 6)! 6!] 0.5^6 0.5^(10 – 6)

P = 0.205

when r = 7

P = [10! / (10 – 7)! 7!] 0.5^7 0.5^(10 – 7)

P = 0.117

when r = 8

P = [10! / (10 – 8)! 8!] 0.5^8 0.5^(10 – 8)

P = 0.044

when r = 9

P = [10! / (10 – 9)! 9!] 0.5^9 0.5^(10 – 9)

P = 9.766 x 10^-3

when r = 10

P = [10! / (10 – 10)! 10!] 0.5^10 0.5^(10 – 10)

P = 9.766 x 10^-4

So the probability that her score will be at least 5 is:

P (r≥5) = 0.246 + 0.205 + 0.117 + 0.044 + 9.766 x 10^-3 + 9.766 x 10^-4

P (r≥5) = 0.623

So about 62.3% chance.

You can do the same for the other item quiz, just set the value of n

7 0

3 years ago

Farmer frank owns a piece of grassland. The grass grows at a constant rate and each cow eats at a constant rate. 12 cows can eat

MrRa [10]

Answer: There are 36 cows that can eaten 72 acres of grass in 126 days.

Step-by-step explanation:

Let x be the amount of grass in an acre initially.

Let y be the amount of grass grown in an acre per day.

Since we have given that

12 cows can eat 10 acres of grass in 28 days

12×28 = 10x + 10×28 y

336 = 10x + 280 y----------------------------(1)

Similarly,

21 cows can eat 30 acres of grass in 63 days.

21×63 = 30x + 30×63 y

1323 = 30x +1890 y ---------------------------(2)

So, by graphing method, we get the value of x and y

$x=\dfrac{126}{5},\ y=\dfrac{3}{10}$

So, we have, 72 acres of grass in 126 days, we need to find the number of cows.

So, it becomes,

c×126 = 72x + 72×126 y

$126c=72\times \dfrac{126}{5}+72\times 126\times \dfrac{3}{10}\\\\126x=4536\\\\x=\dfrac{4536}{126}\\\\x=36$

Hence, there are 36 cows that can eaten 72 acres of grass in 126 days.

3 0

3 years ago

You recently deposited $2000 in a bank account during your first year at work.

lara [203]

Answer:

A. $12,000

B. $147,000

Step-by-step explanation:

8 0

3 years ago

What is the area of the trapezoid?

Ivenika [448]

Answer:

the area of a trapezoid is equal to half the product of the height and the sum of the two bases. Area = ½ x (Sum of parallel sides) x (perpendicular distance between the parallel sides).

8 0

3 years ago

Read 2 more answers

whitney is training to ride her bicycle in a big race. The table below shows hiw many miles she rides each day of one week

hoa [83]

Answer: C (24.5 miles more)

Step-by-step explanation:

on Friday she rode 42.4 miles

on Tuesday she rode 17.9 miles

you just subtract Tuesday’s miles from Friday’s miles

42.4 - 17.9 = 24.5

so, C

7 0

4 years ago

Given: x + y = 10. If x = -21, what is y?