A new concrete mix is being designed to provide adequate compressive strength for concrete blocks. The specification for a particular application calls for the blocks to have a mean compressive strength µ greater than 1350 kPa. A sample of 100 blocks is produced and tested. Their mean compressive strength is 1356 kPa and their standard deviation is 70 kP

Complete question:

new concrete mix is being designed to provide adequate compressive strength for concrete blocks. The specification for a particular application calls for the blocks to have a mean compressive strength µ greater than 1350 kPa. A sample of 100 blocks is produced and tested. Their mean compressive strength is 1356 kPa and their standard deviation is 70 kP

a) Find the p value.

b) Do you believe it is plausible that the blocks do not meet the specification, or are you convinced that they do? Expain your reasoning.

a) p-value= 0.1949

b) It is possible the blocks do not meet the specifications

Explanation:

Given:

n = 100

Sample mean, X' = 1356

Standard deviation, s.d = 70

a) To find p- value.

Null hypothesis:

H0: u ≤ 1350

Alternative hypothesis:

H1 : u > 1350

The test statistic wll be:

=0.86

The p value will be:

= P(z>0.86)

= 1-P(z≤0.86)

Using the normal distribution table, we now have:

1 - 0.8051

= 0.1949

P value = 0.1949

b) Since our p-value is 0.1949, we do not reject the null hypothesis, because the p-value, 0.1949, is not small. This means that it is possible the blocks do not meet the specifications.

  the grams     of oxygen gas   that can be produced     is 20.6   grams of o₂

calculation

2liclo₃ →   2 licl + 3 o₂

step 1:   find the moles of liclo₃

moles = mass÷ molar mass

from periodic table the molar mass of liclo₃ =6.9 +35.5   +(16 x3) =90.4 g/mol

moles=38.7 g÷90.4 g/mol=0.4281   moles

step 2:   use the   mole ratio   to calculate the moles of o2

from equation above, liclo₃: o₂   is 2: 3  

therefore the moles of   o₂=0.4281 moles x3/2 =0.6422   moles

step 3: find mass   of o₂

mass= moles x molar mass

from periodic table the   molar mass of   o₂ = 16 x2= 32 g/mol

mass=0.6422   moles   x   32 g/mol = 20.6 grams of o₂

no. dot product   =0 when vecs at right angles