Photo AI

Acme Confectionery has launched a new bar called Chocolate Crunch - Leaving Cert Mathematics - Question 8 (i) - 2018

Question icon

Question 8 (i)

Acme-Confectionery-has-launched-a-new-bar-called-Chocolate-Crunch-Leaving Cert Mathematics-Question 8 (i)-2018.png

Acme Confectionery has launched a new bar called Chocolate Crunch. The weights of these new bars are normally distributed with a mean of 4-64 g and a standard deviat... show full transcript

Worked Solution & Example Answer:Acme Confectionery has launched a new bar called Chocolate Crunch - Leaving Cert Mathematics - Question 8 (i) - 2018

Step 1

Calculate $z_1$ for 4-6 g

96%

114 rated

Answer

To find z1z_1, we use the formula:

z1=Xμσ/nz_1 = \frac{X - \mu}{\sigma / \sqrt{n}}

Where:

  • X=4.6X = 4.6 g,
  • μ=4.64\mu = 4.64 g,
  • σ=0.12\sigma = 0.12 g,
  • n=10n = 10.

Substituting, we get:

z1=4.64.640.12/10=0.040.03791.05409z_1 = \frac{4.6 - 4.64}{0.12 / \sqrt{10}} = \frac{-0.04}{0.0379} \approx -1.05409.

Step 2

Calculate $z_2$ for 4-7 g

99%

104 rated

Answer

For z2z_2, we apply the same formula:

z2=Xμσ/nz_2 = \frac{X - \mu}{\sigma / \sqrt{n}}

Where:

  • X=4.7X = 4.7 g.

Substituting, we get:

z2=4.74.640.12/10=0.060.03791.581138z_2 = \frac{4.7 - 4.64}{0.12 / \sqrt{10}} = \frac{0.06}{0.0379} \approx 1.581138.

Step 3

Find the probability $p(-1.05 < z < 1.58)$

96%

101 rated

Answer

We can find the probability by using the standard normal distribution table:

  • From the Z-table, P(Z<1.58)0.9429P(Z < 1.58) \approx 0.9429 and P(Z<1.05)0.1487P(Z < -1.05) \approx 0.1487.

Thus, the required probability is:

p(1.05<z<1.58)=P(Z<1.58)P(Z<1.05)=0.94290.1487=0.7942p(-1.05 < z < 1.58) = P(Z < 1.58) - P(Z < -1.05) = 0.9429 - 0.1487 = 0.7942.

This approximates to 0.796 or 79.6%.

Join the Leaving Cert students using SimpleStudy...

97% of Students

Report Improved Results

98% of Students

Recommend to friends

100,000+

Students Supported

1 Million+

Questions answered

Other Leaving Cert Mathematics topics to explore

;