One way of doing it is by using the properties of summing things, like factoring out the minus sign:
<span><span>∑<span>n=2</span>8</span><span>−(n−5)</span>=−<span>∑<span>n=2</span>8</span><span>(n−5)
</span></span>
and splitting it up into two parts and again factor
<span>=−<span>(<span><span>∑<span>n=2</span>8</span><span>n−5<span>∑<span>n=2</span>8</span>1</span></span>)
</span></span>
The last sum is just counting how many numbers there are from 2 to 8, which is 7 (you can do it on your fingers). The first one can be calculated fast if we are clever and use this identity:
<span><span>∑<span>n=1</span>m</span>n=<span><span>m(m+1)</span>2
</span></span>
So what we get is
<span><span>=−<span>(<span>−1+<span><span>8(8+1)</span>2</span>−7</span>)</span>=8−72/2=8−36=−28.</span></span>
3 kilograms... Grams is like ounces and kilograms is like pounds
Answer
16/43
Step-by-step explanation:
17 Male + 27 female = 44 students
now n= 2 so first student was male so one male student was taken out of the equation so 16 male left. now left male students by remaining students so now total left students = 43
so, prob = remaining males/remaining students=16/43
The lifetime is months is 85.24 months
Step-by-step explanation:
In this question you are supposed to find the months "X' that is exceeded by 10% of the hard drives.
Exceeded by 10% means a value X on the frequency distribution table that is to the right of the mean score of 75 months showing 10% more.This means exceeding 10% will be months above 0.9 (from 100-90=90%=1-0.9=0.1 as a decimal)
In the standard normal distribution table, look for 0.9, closest value is 0.8997 which gives z=1.2 for y-axis and for x-axis 0.08 to give 1.28
So you have z=1.28, mean μ=75 and δ=8, finding X will gives
You apply the formula;
P(z>X-75/8)
P(z>1.28)=0.1
z=X-μ /δ
1.28=(X-75)/8
8*1.28=X-75
10.24=X-75
10.24+75=X
X=85.24 months
Learn More
Percentile in Normal distribution :brainly.com/question/13700221
Keywords: normally distributed, mean, standard deviation, exceeds
#LearnwithBrainly
28=(2+x)+x
-2 -2
_________
26=x+x
26=2x
Divide both by 2
13=x
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