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prohojiy [21]
3 years ago
6

suppose medical records indicate that the length of newborn babies (in inches) is normally distributed with a mean of 20 and a s

tandard deviation of 2.6. find the probability that a given infant is between 17.4 and 22.6 inches long
Chemistry
1 answer:
Tanya [424]3 years ago
5 0

Answer:

  • <u>0.6826 (68.26%)</u>

Explanation:

<u>1) Find the z-scores:</u>

  • z = [X - μ ] / σ

a) z-score for 22.6 inches length

  • X = 22.6
  • μ = 20
  • σ = 2.6

  • z = [ 22.6 - 20 ] / 2.6 = 1.00

b) z-score for 17.4 inches length

  • X = 17.4
  • μ = 20
  • σ = 2.6

  • z = [ 17.4 - 20 ] / 2.6 =  - 1.00

<u>2) Probability</u>

Then, you have to find the probability that the length of an infant is between - 1.00 and 1.00 standards deviations (σ) from the mean (μ).

That is a well known value of 68%, which is part of the 68-95-99.7 empirical rule.

The most exact result is obtained from tables and is 68.26%:

  • 1 - P (z ≥ 1.00) - P (z ≤ - 1.00) = 1 - 0.1587 - 0.1587 = 0.6826 = 68.26%
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ahrayia [7]

Answer:

165.726 g.

Explanation:

  • For the balanced equation:

<em>Cr₂O₃ + 3H₂S → Cr₂S₃ + 3H₂O,</em>

It is clear that 1 mol of Cr₂O₃ and 3 mol of H₂S to produce 1 mol of Cr₂S₃ and 3 mol of H₂O.

  • Firstly, we need to calculate the no. of moles of 324.8 g of chromium(III) sulphide:

no. of moles of Cr₂S₃ = mass/molar mass = (324.8 g)/(200.19 g/mol) = 1.62 mol.

  • Now, we can find the "no. of grams" of H₂S are needed:

<u><em>Using cross multiplication:</em></u>

3 mol of H₂S produces → 1 mol of Cr₂S₃, from stichiometry.

??? mol of H₂S produces → 1.62 mol of Cr₂S₃.

∴ The no. of moles of H₂S are needed = (3 mol)(1.62 mol)/(1 mol) = 4.86 mol.

∴ The "no. of grams" of H₂S are needed = (no. of moles of H₂S)(molar mass of H₂S) = (4.86 mol)(34.1 g/mol) = 165.726 g.

7 0
3 years ago
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List the 3 ways carbon can enter the ocean?
prohojiy [21]

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Compute diffusion coefficients for the interdiffusion of carbon in both (a) α-iron (BCC) and (b) γ-iron (FCC) at 800.˚C. Assume
Ne4ueva [31]

Answer:

a)1.404 E-10 m^2/s

b)1.438 E-12 m^2/s

Explanation:

Diffusion Coefficients can be calculated at different temperatures taking into account the energy of the diffusive process, remember that this process takes place in the interstices of the solid, and gets with higher temperatures due to the higher kinetic energy of the particles.

D=D_{o} *exp(-Q/RT)

a) For α-iron (BCC)

D=1.10*10^{-6} m^{2}/s *exp(-80.0kJ/mol/8.314*10^{-3}kJ/mol*k*1073.15K)= 1.404*10^{-10} m^{2}/s

b) For γ-iron (FCC)

D=2.30*10^{-5} m^{2}/s *exp(-148.0kJ/mol/8.314*10^{-3}kJ/mol*k*1073.15K)= 1.438*10^{-12} m^{2}/s

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Why are chemical equations balanced?​
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