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4 years ago

There are 15 girls in a sixth grade class. Only 40% of the class are boys. How many are in the class?

Mathematics

1 answer:

Strike441 [17]4 years ago

6 0

Answer:

hello : in the class: 25

Step-by-step explanation:

60% represent 0.60 in 15 girls

40% represent 0.40 in x boys

so : x = (15×0.40)/0.60 = 10 boys

in the class: 10 boys + 15 girls = 25

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Each morning John eats some eggs. On any given morning, the number of eggs he eats is equally likelyto 1, 2, 3, 4, or 5 independ

qaws [65]

Answer:

Mean = 3

Variance = 2

Step-by-step explanation:

Since number of eggs he eats is equally likely to any 5 numbers, probability of each one will be (1/5) = 0.2

The probability mass function will therefore be

x 1 2 3 4 5

p 0.2 0.2 0.2 0.2 0.2

The mean is given as the expected value

And expected value is given as

E(X) = Σ xᵢpᵢ

where x = each possible sample space

p = probability of the sample space occurring.

E(X) = (1×0.2) + (2×0.2) + (3×0.2) + (4×0.2) + (5×0.2) = 3 eggs.

b) Variance is given by

Variance = Var(X) = Σx²p − μ²

where μ = E(X)

Σx²p = (1² × 0.2) + (2² × 0.2) + (3² × 0.2) + (4² × 0.2) + (5² × 0.2) = 0.2 + 0.8 + 1.8 + 3.2 + 5 = 11

Var(X) = Σx²p − μ² = 11 - 3² = 11 - 9 = 2

5 0

3 years ago

15 point reward + brainliest for the CORRECT answer

jasenka [17]

Answer:

abby has 72 pair of socks

8 0

3 years ago

Read 2 more answers

Please help!! I'm super confused

Alona [7]

Answer:

36cm

Step-by-step explanation:

7cm+11cm = 17cm

8cm +11cm=18cm

18cm+17cm=36cm

5 0

4 years ago

7. All of the following are perfect square trinomials EXCEPT one. Which is it?

wolverine [178]

Answer:

All answers EXCEPT answer C. are perfect square trinomials.

Step-by-step explanation:

A perfect square trinomial is polynomial that satisfies the following condition:

$(a+b)^{2} = a^{2}+2\cdot a \cdot b + b^{2}$ , $\forall\,a,b\in\mathbb{R}$

Let prove if each option observe this:

a) $4\cdot x^{2} + 12\cdot x\cdot y + 9\cdot y^{2}$

1) $4\cdot x^{2} + 12\cdot x\cdot y + 9\cdot y^{2}$ Given

2) $(2\cdot x)^{2}+ 2\cdot (2\cdot x)\cdot (3\cdot y)+(3\cdot y)^{2}$ Definition of power/Distributive, associative and commutative properties.

3) $a = 2\cdot x$ , $b = 3\cdot y$ Definition of perfect square trinomial/Result.

b) $9\cdot a^{2}-36\cdot a + 36$

1) $9\cdot a^{2}-36\cdot a + 36$ Given.

2) $(3\cdot a)^{2}-2\cdot (3\cdot a)\cdot 6 + 6^{2}$ Definition of power/Distributive, associative and commutative properties.

3) $a = 3\cdot a$ , $b = 6$ Definition of perfect square trinomial/Result.

c) $x\cdot y^{2}-4\cdot x^{2}\cdot y^{2}+4\cdot x^{2}\cdot y^{2}$

1) $x\cdot y^{2}-4\cdot x^{2}\cdot y^{2}+4\cdot x^{2}\cdot y^{2}$ Given

2) $x\cdot y\cdot (1-4\cdot x+4\cdot x)$ Distributive property.

3) $x\cdot y \cdot 1$ Existence of the additive inverse/Modulative property.

4) $x\cdot y$ Modulative property/Result.

d) $a^{2}\cdot b^{2}+4\cdot a^{3}\cdot b + 4\cdot a^{4}$

1) $a^{2}\cdot b^{2}+4\cdot a^{3}\cdot b + 4\cdot a^{4}$ Given

2) $(a\cdot b)^{2}+2\cdot (a\cdot b)\cdot (2\cdot a^{2})+(2\cdot a^{2})$ Definition of power/Distributive, associative and commutative properties.

3) $a = a\cdot b$ , $b = 2\cdot a^{2}$ Definition of perfect square trinomial.

All answers EXCEPT answer C. are perfect square trinomials.

8 0

3 years ago

HELP PLEASE! WILL GIVE BRAINLIEST!

Pepsi [2]

Answer:

Exact volume: 804.24772

Approximate volume: 804.248

Step-by-step explanation:

V = 1/3hπr².

5 0

3 years ago