I do not agree. If you divide 240 by 30, it would be 8 heartbeats, which is absurd. It's impossible for something to survive with 8 heartbeats per 30 seconds.
In order to get the CORRECT answer, divide 240 by 60 seconds.
This would give you 4 heartbeats per second.
Then, multiply it by 30 seconds, which would give you 120 heartbeats.

CORRECT answer: 120

5 0

3 years ago

The deck of a bridge is suspended 275 feet above a river. If a pebble falls off the side of the bridge, the height, in feet, of

Ivenika [448]

Answer:

Our equation for the height is:

y(t) = 275 - 16*t^2.

a) To find the average velocity between two times, t1 and t2, (where t2 > t1) the equation is:

$AV = \frac{y(t2) - y(t1)}{t2 - t1}$

Then:

i) t1 = 4s, t2 = 4s + 0.1s = 4.1s

The average velocity is:

$AV = \frac{(275 - 16*4.1^2) - (275 - 16*4^2)}{4.1 - 4} = \frac{16(4^2 - 4.1^2)}{0.1} = -129.6$

And the units will be ft/s, so the average speed is:

-129.6 ft/s

The minus sign is because te pebble is falling down.

ii) t1 = 4s, t2 = 4s + 0.05s = 4.05s

The average velocity is:

$AV = \frac{(275 - 16*4.05^2) - (275 - 16*4^2)}{4.05 - 4} = \frac{16(4^2 - 4.05^2)}{0.05} = -128.8$

So the average speed is -128.9 ft/s

iii) t1 = 4s, t2 = 4s + 0.01s = 4.01s

The average speed is:

$AV = \frac{(275 - 16*4.01^2) - (275 - 16*4^2)}{4.01 - 4} = \frac{16(4^2 - 4.01^2)}{0.01} = -128.16$

The average speed is -128.16 ft/s.

b) The instantaneous velocity of the pebble after 4 seconds can be obtained by looking at the velocity equation, that is the derivative of the height equation.

v(t) = dy(t)/dt.

v(t) = -2*16*t + 0

Then the velocity at t = 4s is:

v(4s) = -32*4 = -128

The instantaneous velocity at t = 4s is -128 ft/s.

3 0

3 years ago

Cheddar Cheese

disa [49]

Complete question :

Cheddar Cheese

$3/lb

Swiss Cheese

$5/lb

Keisha is catering a luncheon. She has $30 to spend on a mixture of Cheddar cheese and Swiss cheese. How many pounds of cheese can Keisha get if she buys only Cheddar cheese? Only Swiss cheese? A mixture of both cheeses?

What linear equation in standard form can she use to model the situation?

Answer:

10 lbs of cheddar cheese

6 lbs of Swiss cheese

$3a + $5b = $30

Step-by-step explanation:

Given that :

Cheddar cheese = $3/lb

Swiss cheese = $5/lb

Total amount budgeted for cheese = $30

How many pounds of cheese can Keisha get if she buys only Cheddar cheese?

Pounds of cheedar cheese obtainable with $30

Total budget / cost per pound of cheddar cheese

$30 / 3 = 10 pounds of cheedar cheese

Only Swiss cheese?

Pounds of cheedar cheese obtainable with $30

Total budget / cost per pound of Swiss cheese

$30 / 5 = 6 pounds of Swiss cheese

A mixture of both cheeses?

What linear equation in standard form can she use to model the situation?

Let amount of cheddar cheese she can get = a

Let amount of Swiss cheese she can get = b

Hence,

(Cost per pound of cheddar cheese * number of pounds of cheddar) + (Cost per pound of Swiss cheese * number of pounds of Swiss cheese) = total budgeted amount

(3 * a) + (5 * b) = $30

$3a + $5b = $30

4 0

3 years ago