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3 years ago

F x is a prime number, then x + 1 is not a prime number. A counterexample is x =

Mathematics

2 answers:

Finger [1]3 years ago

7 0

Answer:

A counterexample is x = 3

Step-by-step explanation:

We are given that x is a prime number, and x + 1 is not a prime number. However consider the number 3. We know that 3 is a prime number, as it is present as factors of 1 and itself. However 3 + 1 = 4 - which falls into the category of a composite number, as it can divide into 2 * 2. Therefore your counterexample could be x = 3.

svlad2 [7]3 years ago

3 0

Answer:

x=2

Step-by-step explanation:

x=2

x+1=3

and 3 is a prime

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Answer:

The probability that seven or more of them used their phones for guidance on purchasing decisions is 0.7886.

Step-by-step explanation:

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$P(x=k)=\dbinom{n}{k} p^{k}q^{n-k}$

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$P(x\geq7)=\sum_{k=7}^{14}P(x=k)\\\\\\$

$P(x=7)=\dbinom{14}{7} p^{7}q^{7}=3432*0.0195*0.0027=0.1824\\\\\\P(x=8) = \dbinom{14}{8} p^{8}q^{6}=3003*0.0111*0.0063=0.2115\\\\\\P(x=9) = \dbinom{14}{9} p^{9}q^{5}=2002*0.0064*0.0147=0.1869\\\\\\P(x=10) = \dbinom{14}{10} p^{10}q^{4}=1001*0.0036*0.0342=0.1239\\\\\\P(x=11) = \dbinom{14}{11} p^{11}q^{3}=364*0.0021*0.0795=0.0597\\\\\\P(x=12) = \dbinom{14}{12} p^{12}q^{2}=91*0.0012*0.1849=0.0198\\\\\\P(x=13) = \dbinom{14}{13} p^{13}q^{1}=14*0.0007*0.43=0.004\\\\\\$

$P(x=14) = \dbinom{14}{14} p^{14}q^{0}=1*0.0004*1=0.0004\\\\\\$

$P(x\geq7)=0.1824+0.2115+0.1869+0.1239+0.0597+0.0198+0.004+0.0004\\\\P(x\geq7)=0.7886$

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