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If alvin sold 60% of his baseball cards, gave away 30% of those that were left, and still had 40 baseball cards in his possessio

kipiarov [429]

Answer:

The number of baseball card to begin with is 143

Step-by-step explanation:

Let The number of baseball cards = x

The number of sold baseball card = 60% of x

= 0.6 x

The number of left baseball card = x - 0.6 x = 0.4 x

The number of card gave away = 30 % of left cards

= 0.3 × 0.4 x = 0.12 x

The number of card left in his possession = 40

So, 0.6 x + 0.12 x + 40 = x

Or, 40 = x - 0.6 x - 0.12 x

Or, 40 = 0.28 x

∴ x = $\frac{40}{0.28}$ = 142.85 ≈ 143

Hence The number of baseball card to begin with is 143 Answer

3 0

3 years ago

HELP !! im going to post a picture of this math problem . i need an answer and explanation asap ..

Diano4ka-milaya [45]

The 3rd one is the correct answer

3 0

3 years ago

If 6xa=54 and b-a=14 what is axb

bagirrra123 [75]

6a=54 so a=54/6, a=9

b-a=14, and using a found above...

b-9=14

b=23, so a=9 and b=23 so

ab=9(23)=207

6 0

3 years ago

Read 2 more answers

The Wall Street Journal reported that automobile crashes cost the United States $162 billion annually (2008 data). The average c

ivanzaharov [21]

Answer:

$n=(\frac{2.326(500)}{120})^2 =93.928 \approx 94$

So the answer for this case would be n=94 rounded up to the nearest integer

Step-by-step explanation:

Information given

$\bar X$ represent the sample mean

$\mu$ population mean (variable of interest)

$\sigma= 500$ represent the population standard deviation

n represent the sample size

Solution to the problem

The margin of error is given by this formula:

$ME=z_{\alpha/2}\frac{s}{\sqrt{n}}$ (a)

And on this case we have that ME =120 and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=(\frac{z_{\alpha/2} \sigma}{ME})^2$ (b)

The confidence2 level is 98% or 0.98 then the significance level would be $\alpha=1-0.98=0.02$ and $\alpha/2=0.01$ , the critical value for this case would be $z_{\alpha/2}=2.326$ , replacing into formula (b) we got:

$n=(\frac{2.326(500)}{120})^2 =93.928 \approx 94$

So the answer for this case would be n=94 rounded up to the nearest integer

8 0

3 years ago

A projectile is launched into the air. The function h(t) = –16t2 + 32t + 128 gives the height, h, in feet, of the projectile t s

Zinaida [17]

Answer:

t = 4 seconds

Step-by-step explanation:

The height of the projectile after it is launched is given by the function :

$h(t)=-16t^2+32t+128$

t is time in seconds

We need to find after how many seconds will the projectile land back on the ground. When it land, h(t)=0

So,

$-16t^2+32t+128=0$

The above is a quadratic equation. It can be solved by the formula as follows :

$t=\dfrac{-b\pm \sqrt{b^2-4ac} }{2a}$

Here, a = -16, b = 32 and c = 128

$t=\dfrac{-32\pm \sqrt{(32)^2-4\times (-16)(128)} }{2\times (-16)}\\\\t=\dfrac{-32+ \sqrt{(32)^2-4\times (-16)(128)} }{2\times (-16)}, \dfrac{-32\- \sqrt{(32)^2-4\times (-16)(128)} }{2\times (-16)}\\\\t=-2\ s\ \text{and}\ 4\ s$

Neglecting negative value, the projectile will land after 4 seconds.

4 0

3 years ago