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2 years ago

A thread is being pulled off a spool at the rate of 40 cm per second. Find the radius of the spool

Mathematics

1 answer:

murzikaleks [220]2 years ago

3 0

Answer:

r = 0.0424 cm (3sf)

Step-by-step explanation:

it makes 150 rev/sec

1 revolution = 1 circumference = 2pi*r

so every second the spool goes through 2*pi*r*150 of distance

we know that the rate of pulling is 40cm/sec

so 2pi*r*150 = 40

r = 40/(2pi*150), which is 0.04244131816 cm.

check: Circumference is 2pi*r = 0.2666

now multiply by 150rev/sec = 40 cm/sec

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Alex buys 2 1/2 pounds of grapes. He buys 1 1/4 times as many pounds of apples as grapes. How many pounds of apples does he buy?

galina1969 [7]

Given:
grapes = 2 1/2 pounds
apples = 1 1/4 times as many pounds as grapes.

For easier computation, let us convert these fractions into numbers with decimal places.

2 1/2 pounds = 2.50 pounds
1 1/4 times = 1.25

Apples = 2.50 pounds * 1.25 = 3.125 pounds of apples.

Or we still use fractions. We need to convert the mixed fractions into improper fractions.

2 1/2 = 5/2
1 1/4 = 5/4

5/2 * 5/4 = 5*5 / 2*4 = 25/8 is simplified to 3 1/8 pounds

3 0

3 years ago

.Damian wrote the number five and thirty-eight thousandths as 5.38. Was he correct or not? if so, what was the error

eduard

Answer:

he is incorrect.

Step-by-step explanation:

It would be 5 and 38 HUNDRETHS because the first number after the decimal is the tenths.

5 0

3 years ago

7+2x/3=5 .............

borishaifa [10]

Answer:

x= -3

Step-by-step explanation:

7 + 2x/3 = 5

Subtract 7 from both sides,

2x/3 = 5-7

2x/3 = -2

Multiply by 3,

2x = -2*3

Divide by 2,

x = -2*3 / 2

x = -3

5 0

3 years ago

Ping lives at the corner of 3rd Street and 6th Avenue. Ari lives at the corner of 21st Street and 18th Avenue. There is a gym Tw

mr_godi [17]

Answer: (15th street, 14th Avenue)

Step-by-step explanation:

Given the following :

Ping's residence = (3rd street, 6th Avenue)

Ari's residence = (21st street, 18th Avenue)

Gym location = 2/3 the distance of Ping's residence to Ari's residence

So, distance between Ping's home to Ari's home

Distance = (21st street, 18th Avenue) - (3rd street, 6th Avenue)

Distance = (21 - 3) street, (18 - 6) avenue

Distance between ping and Ari = (18th , 12th )

Gym distance = 2/3 of distance between ping and Ari

Gym distance = 2/3 × (18), 2/3 ×(12)

Gym distance = (12, 8)

Gym location = Ping's location + gym distance

Gym location = (3rd street, 6th Avenue) + (12th street, 8th Avenue)

Gym location = (15th street, 14th Avenue)

3 0

3 years ago

A limnologist wishes to estimate the mean phosphate content per unit volume of lake water. It is knownfrom studies in previous y

telo118 [61]

Answer: 68

Step-by-step explanation:

As per given , we have

Population standard deviation : $\sigma=4$

Critical value for 90% confidence interval = $z_{\alpha/2}=1.645$

Margin of error : E= 0.8 milligrams

The formula to find the sample size is given by :-

$n=(\dfrac{z_{\alpha/2}\ \sigma}{E})^2$

i.e. $n=(\dfrac{(1.645)(4)}{0.8})^2=(8.225)^2$

$=67.650625\approx68$

Hence, the limnologist must analyze 68 samples.

6 0

4 years ago