Question

When a specific variety of radish is grown without

fertilizer, the weights of the radishes produced are
, normally distributed with mean 40 g and standard
deviation 10 g.
Determine the proportion of radishes grown:
a) Without fertilizer with weights less than 50 grams
C
b) Without fertilizer with weights between 20 and 60 g
c) Without fertilizer with weights greater than 60 g
0
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When the same variety of radish is grown in the same
way but with fertilizer added, the weights of the
radishes produced are also normally distributed, but
with mean 140 g and standard deviation 40g.
Determine the proportion of radishes grown:
d) With fertilizer with weights less than 60 grams
e) With fertilizer with weights between 20 and 60 g
f) With fertilizer with weights greater than 60 g

Answer 1

Explanation:

a) Without fertilizer with weights less than 50 grams:

Let X be the weight of radishes produced without fertilizer. Then, X ~ N(40, 10^2).

We need to find P(X < 50).

Using the standard normal distribution, we have:

Z = (X - 40)/10

P(X < 50) = P(Z < (50-40)/10) = P(Z < 1) = 0.8413 (using a standard normal table or calculator)

Therefore, the proportion of radishes grown without fertilizer with weights less than 50 grams is 0.8413.

b) Without fertilizer with weights between 20 and 60 g:

We need to find P(20 < X < 60).

Using the standard normal distribution, we have:

Z1 = (20 - 40)/10 = -2

Z2 = (60 - 40)/10 = 2

P(20 < X < 60) = P(-2 < Z < 2) = 0.9544 (using a standard normal table or calculator)

Therefore, the proportion of radishes grown without fertilizer with weights between 20 and 60 grams is 0.9544.

c) Without fertilizer with weights greater than 60 g:

We need to find P(X > 60).

Using the standard normal distribution, we have:

Z = (60 - 40)/10 = 2

P(X > 60) = P(Z > 2) = 0.0228 (using a standard normal table or calculator)

Therefore, the proportion of radishes grown without fertilizer with weights greater than 60 grams is 0.0228.

d) With fertilizer with weights less than 60 grams:

Let Y be the weight of radishes produced with fertilizer. Then, Y ~ N(140, 40^2).

We need to find P(Y < 60).

Using the standard normal distribution, we have:

Z = (60 - 140)/40 = -2

P(Y < 60) = P(Z < -2) = 0.0228 (using a standard normal table or calculator)

Therefore, the proportion of radishes grown with fertilizer with weights less than 60 grams is 0.0228.

e) With fertilizer with weights between 20 and 60 g:

We need to find P(20 < Y < 60).

Using the standard normal distribution, we have:

Z1 = (20 - 140)/40 = -3

Z2 = (60 - 140)/40 = -2

P(20 < Y < 60) = P(-3 < Z < -2) = 0.0668 (using a standard normal table or calculator)

Therefore, the proportion of radishes grown with fertilizer with weights between 20 and 60 grams is 0.0668.

f) With fertilizer with weights greater than 60 g:

We need to find P(Y > 60).

Using the standard normal distribution, we have:

Z = (60 - 140)/40 = -2

P(Y > 60) = P(Z > -2) = 0.9772 (using a standard normal table or calculator)

Therefore, the proportion of radishes grown with fertilizer with weights greater than 60 grams is 0.9772.