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3 years ago

Derick studied 13 1/2 hours this week for a spelling bee. Write the number of hours as a decimal.

Mathematics

1 answer:

serg [7]3 years ago

3 0

Answer:

13.5

Step-by-step explanation:

When you convert fraction numbers to decimal numbers, remember they are written like this:

whole . parts

In 13 1/2, you have 13 wholes and 1/2 parts. The decimal number would look like 13 . parts

To find the decimal for 1/2, put into your calculator 1 ÷ 2. The answer will be 0.5 Write "5" for parts. The decimal where 0.5 is will line up with the decimal in the decimal number.

13.5

Derek studied 13.5 hours for the spelling bee.

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** BRAINLIEST!! **

densk [106]

we have three sides, let's look at the two smaller sides first.

check the picture below atop

if we move the sides closer and ever closer to each other, to the extent that one is right on top of the other, what is the length of the red side? Well, assuming the two smaller sides are one pancaked on top of the other, the red side will be as long as 9 - 4 = 5. However, the sides can't be on top of each other, because if that's so, we have a flat-line, and thus we wouldn't have a triangle. So whatever the third side may be, it must be greater than 5.

check the picture below at the bottom

Now, if we move the sides away from each other, farther and farther to the extent that one is parallel to the other, then the third side will just be as long as 4 + 9 = 13. However, we can't do that, because if that were to happen, we again will have a flat-line and not a triangle. So whatever the third side may be, it must be less than 13.

4 0

2 years ago

Last month, he sold 50 chickens and 30 ducks for $550. This month, he sold 44 chickens and 36 ducks for

STALIN [3.7K]

Answer: chicken $8, duck $5

Explanation:

x - the cost of a chicken
y - the cost of a duck

he sold 50 chickens and 30 ducks for $550: 50x + 30y = 550
he sold 44 chickens and 36 ducks for $532: 44x + 36y = 532

50x + 30y = 550 divide by 10
44x + 36y = 550 divide by 4
______________
50x/10 + 30y/10 = 550/10
44x/4 + 36y/4 = 532/4
______________
5x + 3y = 55
Multiply by (-3)
11x + 9y = 133
______________
5x * (-3) + 3y * (-3) = 55 * (-3)
11x + 9y = 133
______________
-15x - 9y = -165
11x + 9y = 133
______________
Sum up:
-4x + 0y = -32
-4x = -32
x = -32/-4
x = 8

Since 5x + 3y = 55 and x = 8, then:
5 * 8 + 3y = 55
40 + 3y = 55
3y = 55 - 40
3y = 15
y = 15/3
y = 5

6 0

3 years ago

Read 2 more answers

What is the solution for the system of equations {9x+8y=3 6x−12y=−11?

lions [1.4K]

Answer:

( - $\frac{1}{3}$ , $\frac{3}{4}$ )

Step-by-step explanation:

Given the 2 equations

9x + 8y = 3 → (1)

6x - 12y = - 11 → (2)

To eliminate the y- term multiply (1) by 1.5

13.5x + 12y = 4.5 → (3)

Add (2) and (3) term by term

(6x + 13.5x) + (- 12y + 12y) = (- 11 + 4.5)

19.5x = - 6.5 ( divide both sides by 19.5 )

x = $\frac{-6.5}{19.5}$ = - $\frac{1}{3}$

Substitute this value into either of the 2 equations and solve for y

Using (1), then

- 3 + 8y = 3 ( add 3 to both sides )

8y = 6 ( divide both sides by 8 )

y = $\frac{6}{8}$ = $\frac{3}{4}$

Solution is (- $\frac{1}{3}$ , $\frac{3}{4}$ )

6 0

3 years ago

The life of a red bulb used in a traffic signal can be modeled using an exponential distribution with an average life of 24 mont

BartSMP [9]

Answer:

See steps below

Step-by-step explanation:

Let X be the random variable that measures the lifespan of a bulb.

If the random variable X is exponentially distributed and X has an average value of 24 month, then its probability density function is

$\bf f(x)=\frac{1}{24}e^{-x/24}\;(x\geq 0)$

and its cumulative distribution function (CDF) is

$\bf P(X\leq t)=\int_{0}^{t} f(x)dx=1-e^{-t/24}$

• What is probability that the red bulb will need to be replaced at the first inspection?

The probability that the bulb fails the first year is

$\bf P(X\leq 12)=1-e^{-12/24}=1-e^{-0.5}=0.39347$

• If the bulb is in good condition at the end of 18 months, what is the probability that the bulb will be in good condition at the end of 24 months?

Let A and B be the events,

A = “The bulb will last at least 24 months”

B = “The bulb will last at least 18 months”

We want to find P(A | B).

By definition P(A | B) = P(A∩B)P(B)

but B⊂A, so A∩B = B and

$\bf P(A | B) = P(B)P(B) = (P(B))^2$

We have

$\bf P(B)=P(X>18)=1-P(X\leq 18)=1-(1-e^{-18/24})=e^{-3/4}=0.47237$

hence,

$\bf P(A | B)=(P(B))^2=(0.47237)^2=0.22313$

• If the signal has six red bulbs, what is the probability that at least one of them needs replacement at the first inspection? Assume distribution of lifetime of each bulb is independent

If the distribution of lifetime of each bulb is independent, then we have here a binomial distribution of six trials with probability of “success” (one bulb needs replacement at the first inspection) p = 0.39347

Now the probability that exactly k bulbs need replacement is

$\bf \binom{6}{k}(0.39347)^k(1-0.39347)^{6-k}$

Probability that at least one of them needs replacement at the first inspection = 1- probability that none of them needs replacement at the first inspection.

This means that,

Probability that at least one of them needs replacement at the first inspection =

$\bf 1-\binom{6}{0}(0.39347)^0(1-0.39347)^{6}=1-(0.60653)^6=0.95021$

5 0

3 years ago

Find the axis of symmetry for this parabola:

aalyn [17]

The graph of the given Quadratic equation is attached in the Answer, where we can se that the axis of symmetry is :

x = 1

3 0

3 years ago