Practise questions | Salam Academy

SA-9709-P6-HT-0044 marksL3 ExamCalculatorTests for a mean

A machine fills bags with mean

200

g and standard deviation

12

g. After servicing, a sample of

16

bags has mean

205

g. Test at the

5\%

level whether the mean has increased.

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SA-9709-P6-HT-0063 marksL3 ExamCalculatorErrors

H_0:p=0.25

,

H_1:p<0.25

, with

n=15

.

H_0

is rejected if

X\le1

. Find the probability of a Type I error, correct to 3 significant figures.

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SA-9709-P6-HT-0073 marksL3 ExamCalculatorErrors

For the test in the previous question, the true value of

p

is

0.1

. Find the probability of a Type II error, correct to 3 significant figures.

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SA-9709-P6-LC-0034 marksL3 ExamCalculatorTotals

The masses of bags of rice are

N(200,25)

grams. Find the probability that the total mass of

4

randomly chosen bags is less than

790

g, correct to 3 significant figures.

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SA-9709-P6-LC-0044 marksL3 ExamCalculatorNormal combinations

X\sim N(50,9)

and

Y\sim N(45,16)

are independent. Find

P(X>Y)

, correct to 3 significant figures.

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SA-9709-P6-PO-0064 marksL3 ExamCalculatorNormal for Poisson

X\sim\text{Po}(40)

. Use a normal approximation to find

P(X\le35)

, correct to 3 significant figures.

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SA-AB-BG-0051 markL3 ExamCalculatorSecond messengers

An enzyme cascade is useful because it

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SA-AB-CA-0052 marksL3 ExamCalculatorCalvin cycle

Each CO₂ fixed needs 3 ATP and 2 reduced NADP. How many ATP are needed per glucose?

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SA-AB-EC-0032 marksL3 ExamCalculatorEnergy transfer

A cow ingests 3000 kJ; 1800 kJ are lost in faeces and urine, 900 kJ in respiration. Calculate its net production (kJ).

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SA-AB-KR-0042 marksL3 ExamCalculatorKrebs

How many reduced NAD are made per glucose in glycolysis, link reaction and Krebs cycle combined?

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SA-AB-MB-0022 marksL3 ExamCalculatorCalculations

0.1 cm³ of a 10⁻⁵ dilution produces 45 colonies. Calculate cells per cm³ in the original culture (×10⁷).

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SA-AB-ME2-0052 marksL3 ExamCalculatorVariation

Humans have n = 23. How many chromosome combinations (in millions, to 3 s.f.) are possible in gametes from independent assortment?

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SA-AB-PL-0033 marksL3 ExamCalculatorStatistics

Means 12.0 and 10.0; variances 4.0 and 5.0; n = 10 in each group. Calculate t.

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SA-AB-PT-0043 marksL3 ExamCalculatorTranspiration

A potometer bubble moves 30 mm in 5 min in a capillary of radius 0.5 mm. Calculate the rate of water uptake (mm³ min⁻¹).

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SA-AB-SE-0022 marksL3 ExamCalculatorHardy–Weinberg

Using q = 0.2, calculate the frequency of heterozygous carriers.

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SA-AC-BH-0023 marksL3 ExamCalculatorBorn–Haber cycles

Calculate the lattice energy of KCl (kJ mol⁻¹):

\Delta_fH=-437

;

\Delta_\text{at}H(\mathrm{K})=+89

; IE(K)

=+419

;

\Delta_\text{at}H(\mathrm{Cl})=+122

; EA(Cl)

=-349

.

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SA-AC-EN-0053 marksL3 ExamCalculatorHess's law

Calculate

\Delta_fH

of ethanol:

\mathrm{2C+3H_2+\frac12O_2\rightarrow C_2H_5OH}

.

\Delta_cH

: C −394, H₂ −286, C₂H₅OH −1367 kJ mol⁻¹.

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SA-AC-EZ-0033 marksL3 ExamCalculatorProduct quantities

How long (s) must a 0.500 A current flow to deposit 1.08 g of silver? (

A_r

Ag 108)

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SA-AC-EZ-0053 marksL3 ExamCalculatorProduct quantities

What volume (cm³ at r.t.p.) of oxygen is produced at the anode when 0.400 A flows for 9650 s through dilute H₂SO₄?

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SA-AC-G8-0053 marksL3 ExamCalculatorThermal stability

Calculate the total volume of gas (cm³ at r.t.p.) produced when 0.0200 mol of Ca(NO₃)₂ decomposes.

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