The positive three-digit integer ABC has a ones digit of 1. What is the probability that ABC is divisible by 7? Express your answer as a common fraction.
105 112 119 126 133 140 147 154 161 168 175 182 189 196 203 210 217 224 231 238 245 252 259 266 273 280 287 294 301 308 315 322 329 336 343 350 357 364 371 378 385 392 399 406 413 420 427 434 441 448 455 462 469 476 483 490 497 504 511 518 525 532 539 546 553 560 567 574 581 588 595 602 609 616 623 630 637 644 651 658 665 672 679 686 693 700 707 714 721 728 735 742 749 756 763 770 777 784 791 798 805 812 819 826 833 840 847 854 861 868 875 882 889 896 903 910 917 924 931 938 945 952 959 966 973 980 987 994 Total = 128 - all 3-digit multiples of 7.
161 231 301 371 441 511 581 651 721 791 861 931 Total =12 multiples of 7 ending in 1
Probability = 12 / 128 = 3 / 32
