Be careful about double counting
Probability
Level
1
Among numbers 1 to 1000 how many are divisible by 3 or 7?
428
333
142
475
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1 solution
So we're looking for values between 0 and 1000 divisible by 3 OR 7. Find values divisible by 3 between 0 and 1000, by finding what value times three gets closest to 100 in this case its 333 which times three gives 999. and do the same for seven, value for seven= 142. this tells us there are 333 values divisible by three and 142 divisible by seven. Since the question asks "OR" NOT "AND" we must subtract the number of integers divisible by both 3 and 7. By doing 21 *x = closest factor of 21 to 1000. we get 47. (142+333)-47 = 428