Help solving the problem for number 1-3

Mathematics

1 answer:

lbvjy [14]3 years ago

8 0

1. 4 boxes for 12.....12/4 = 3...paid 3 per box
if 6 were bought....6 * 3 = 18 bucks would be spent

2. 2/9 of 36..." of " means multiply
2/9 * 36 = 72/9 = 8 expected to forget their bows

3. 8 packs for 32.....32/8 = 4 per pack
if 14 packs were bought.....14 * 4 = 56 bucks would be spent

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A polymer is manufactured in a batch chemical process. Viscosity measurements show that it is approximately normally distributed

PilotLPTM [1.2K]

Answer: (751.05, 766.95)

Step-by-step explanation:

We know that the confidence interval for population mean is given by :-

$\overline{x}\pm z*\dfrac{\sigma}{\sqrt{n}}$ ,

where $\sigma$ =population standard deviation.

$\overline{x}$ = sample mean

n= sample size

z* = Two-tailed critical z-value.

Given : $\sigma= 20$

n= 42

$\overline{x}=759$

We know that from z-table , the two-tailed critical value for 99% confidence interval : z* =2.576

Now, the 99% confidence interval around the true population mean viscosity :-

$759\pm (2.5760)\dfrac{20}{\sqrt{42}}\\\\=759\pm (2.5760)(3.086067)\\\\=759\pm7.9497=(759-7.9497,\ 759+7.9497)\]\\=(751.0503,\ 766.9497)\approx(751.05,\ 766.95)$