Question-65423

Question Number 65423 by byaw last updated on 29/Jul/19

Commented by mr W last updated on 29/Jul/19

a l l p r i m e s a r e n o t d i v i s i b l e

b y 3 a n d 5 .

Answered by mr W last updated on 29/Jul/19

f r o m 1 t o 30 t h e r e a r e 10 p r i m e s . t h e y

a r e a l l n o t d i v i s i b l e b y 3 a n d 5 .

p = \frac{10}{30} = \frac{1}{3}

Commented by Rasheed.Sindhi last updated on 30/Jul/19

S i r, I t h i n k t h a t t h e r e a r e 8 s u c h p r i m e s

(E x c l u d i n g 3 a n d 5 b e c a u s e t h e y a r e

d i v i s i b l e b y 3 a n d 5 r e s p e c t l y)

2, 7, 11, 13, 17, 19, 23, 29 .

Commented by MJS last updated on 30/Jul/19

mathematical language has to be accurate

“ 3 and 5^{″} \neq “ 3 or 5^{″} \neq “ 3 xor 5^{″}

x divisible by 3 and 5 \Rightarrow x = 15 n

x divisible by 3 or 5 \Rightarrow x = 3 n or x = 5 n or x = 15 n

x divisible by 3 xor 5 \Rightarrow (x = 3 n or x = 5 n) and x \neq 15 n

[n, k \in Z]

Commented by Rasheed.Sindhi last updated on 30/Jul/19

{Y o u}^{'} r e v e r y r i g h t s i r . I {d i d n}^{'} t c a r e o f t h a t!

Commented by mr W last updated on 30/Jul/19

i a g r e e w i t h M J S s i r .

w h a t R a s h e e d s i r m e a n s i s p r o b a b l y

w h a t t h e q u e s t i o n r e a l l y m e a n s, b u t

t h e q u e s t i o n u s e s a n i n a c c u r a t e

l a n g u a g e .

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