All categories

3 years ago

There are 8 books on a shelf, of which 2 are paperbacks and 6 are hardbacks. how many possible selections of 4 books from this s

helf include at least one paperback?

Mathematics

1 answer:

trapecia [35]3 years ago

8 0

$\displaystyle \binom{6}{3}\cdot2+\binom{6}{2}=\dfrac{6!}{3!3!}\cdot2+\dfrac{6!}{2!4!}=\dfrac{4\cdot5\cdot6}{2\cdot3}\cdot2+\dfrac{5\cdot6}{2}=40+15=55$

You might be interested in

I'm really having trouble simplifying trigonometric expressions, I understand the identities, but sometimes I get stuck, and rea

Karolina [17]

$\bf \cfrac{sin(t)+tan(t)}{tan(t)}\impliedby \textit{distributing the denominator}
\\\\\\
\cfrac{sin(t)}{tan(t)}+\cfrac{tan(t)}{tan(t)}\implies \cfrac{sin(t)}{\frac{sin(t)}{cos(t)}}+1\implies 
\cfrac{\frac{sin(t)}{1}}{\frac{sin(t)}{cos(t)}}+1
\\\\\\
\cfrac{sin(t)}{1}\cdot \cfrac{cos(t)}{sin(t)}+1\implies cos(t)+1$

8 0

3 years ago

If angle a = 11°, what does angle b equal?

N76 [4]

The answer is 169 because 180-11=169

6 0

3 years ago

Read 2 more answers

Nadia makes a monthly income of $4,000. How much will Nadia have for impulse shopping after she pays all of her bills for the mo

Llana [10]

You add all the percentages up and it will give you 64. take 64 and put it over 100 because percentages as a fraction will always be the amount over a 100.
so its 64/100 multiply by 4000/1. 64*4000= 256000 over 100. 256000 divided by 100 = 2560

$2560

7 0

3 years ago

Solve the equation : x^(2)+5=3(x^(2)-3)

Fittoniya [83]

Answer:

x = ± 2

Step-by-step explanation:

Given

x² + 5 = 3x² - 3 ( subtract x² + 5 from both sides )

0 = 2x² - 8 ( add 8 to both sides )

8 = 2x² ( divide both sides by 2 )

4 = x² ( take the square root of both sides )

x = ± $\sqrt{4}$ = ± 2

6 0

3 years ago

Tim purchases 3,000 shares in company X at $2.49 per share. The company subsequently announces a profit warning, and the share p

anygoal [31]

Answer:

$750

Step-by-step explanation:

Tim's share price changes by $2.24 -2.49 = -0.25, so the change in the value of his investment is ...

(3000 shares)(-0.25/share) = -$750

Tim takes a loss of $750 when he sells.

3 0

3 years ago