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3 years ago

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An element with a mass of 630 grams decays by 30% per minute. To the nearest minute, how long will it be untill there are 30 gra

ms of the element remaining?

1 answer:

nataly862011 [7]3 years ago

6 0

Answer:

It should take somewhere between 8 to 9 minutes to decay until there are 30 grams remaining.

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Olegator [25]

Answer:

$r=3.5\%$

Step-by-step explanation:

we know that

The simple interest formula is equal to

$I=P(rt)$

where

I is the Final Interest Value

P is the Principal amount of money to be invested

r is the rate of interest

t is Number of Time Periods

in this problem we have

$t=5\ years\\ P=\$1,200\\ I=\$210\\r=?$

substitute in the formula above

$210=1,200(5r)$

solve for r

$r=210/6,000$

$r=0.035$

convert to percentage (multiply by 100)

$r=3.5\%$

6 0

3 years ago

Fine the equation of the line through (o, -3) perpendicular to y =4x+4

svlad2 [7]

Answer:

The equation of the line is $y = -\frac{x}{4} - 3$

Step-by-step explanation:

Equation of a line:

The equation of a line has the following format:

$y = mx + b$

In which m is the slope and b is the y-intercept(the value of y when x = 0).

Perpendicular lines:

If two lines are perpendicular, the multiplication of their slopes is -1.

Line perpendicular to y = 4x + 4.

This line has slope 4, so our line will have slope:

$4m = -1$

$m = -\frac{1}{4}$

So

$y = -\frac{x}{4} + b$

Through (0, -3)

This means that $b = -3$

So

$y = -\frac{x}{4} - 3$

8 0

3 years ago

Janet wanted to determine her average phone call length over 90 days. She collected the phone bills and randomly picked ten entr

muminat

oops sorry wrong question. sorry if I confused anyone :(

3 0

2 years ago

When two computers are working together, they can finish updating software in 9 minutes. How long would they take individually t

tensa zangetsu [6.8K]

First computer takes x min. For 1 min it does 1/x part of work.

Second computer takes (x+24) min. For one min it does 1/(x+24) part of work.

Both computers for one min do (1/x+1/(x+24)) part of work.

At the same time, both computers for one min do 1/9 part of work.

$\frac{1}{x} + \frac{1}{x+24} = \frac{1}{9} 
\\ \\ \frac{x+24+x}{x(x+24)} = \frac{1}{9} 
\\ \\9(2x+24)=x^{2} +24x
\\ \\ 18x+216=x^{2} +24x
\\ \\ x^{2}+6x-216=0
\\ \\ D=b^{2}-4ac=36+4*216 = 900
\\ \\ x= \frac{-b+/- \sqrt{D} }{2a} = \frac{-6+/-30}{2} 
\\ \\ x_{1}=-18, x_{2}=12

We can use only positive number here. So, 

for the first computer x=12 min,

 for second computer x+24=12+24= 36 min

Answer 12 min and 36 min.$

7 0

3 years ago

If p(x) = x 3 + x 2+ root 5 x + root 5 , then find p( – 5 )

Morgarella [4.7K]

Answer:

-100-4√5

Step-by-step explanation:

Given the polynomial expression

p(x) = x³+x²+√5x + √5

p(-5) = (-5)³+(-5)² + √5(-5) + √5

p(-5) = -125 + 25 -5√5 + √5

p(-5) = -100-4√5

This gives the required answer

6 0

3 years ago