Answer:
About twenty-one percent of twelve month old boys are shorter than 28.8 inches.
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean
and standard deviation
, the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this problem, we have that:

About twenty-one percent of twelve month old boys are shorter than what height?
This is the value of X when Z has a pvalue of 0.21. So it is X when Z = -0.805.




About twenty-one percent of twelve month old boys are shorter than 28.8 inches.
Given/equations formed from text:
I: l=w+3
II: A=l*w
III: new area B=(l-2)*w
IV: B=A-30
substitute l in II with I to remove l:
II': A=l*w=
(w+3)*w=
w^2+3w
substitute l in III with I to remove l:
III': B=(l-2)*w=
(w+3-2)*w=
(w+1)*w=
w^2+w
substitute A and B from II' and III' into IV:
B=A-30
w^2+w=w^2+3w-30
30=2w
w=15
insert w=15 into I:
l=15+3=18
->
A) dimensions of full size rectangle are width 15 and length 18
dimensions of reduced size rectangle are width 15 and length 16
B) full size: 15*18=10*18+5*18=180+90=270cm^2
reduced size: 15*16=10*16+5*16=160+80=240cm^2
Answer:
3/4
Step-by-step explanation:
Given the following :
Number of boxes = 2
First box :
White balls = 3
Blue balls = 2
Second box:
White balls = 4
Blue balls = 1
What is the probability that Frida picked a ball from the first box if she has selected a blue ball?
Probability (P) = (required outcome / Total possible outcomes)
Probability of picking first box : P(F) = 1/2
Probability of not picking second box :P(S) 1/2
Probability of picking blue from first box : P(B | F) = 3/5
Probability of picking blue, but not from first box : P(Blue not from second box) P(B|S) = 1/5
probability that Frida picked a ball from the first box if she has selected a blue ball?
P(F) * P(B|F) ÷ (P(F) * P(B|F)) + (P(S) * P(B|S))
(1/2 * 3/5) ÷ ((1/2 *3/5) + (1/2 * 1/5)
3/10 ÷ (3/10 + 1/10)
3/10 ÷ 4/10
3/10 * 10/4
= 3/4
15% is equal to 15/100 or .15
To find a part of a number, multiply the decimal form of the percentage by the number, or 60* 0.15. The answer is 9
Model:
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There are 60 items, and 15% of them are question marks.