Multiple choice

Choose the correct alternatives from given ones that will complete the series. 30, 68,138,222, ? , 520, 738

  1. 420

  2. 350

  3. 250

  4. 280
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The pattern is: 30(+38)=68, 68(+70)=138, 138(+84)=222. The differences themselves follow a pattern: 38, 70, 84. These are (38+32)=70, (70+14)=84. The next difference should be 84-32=52 or follow another pattern. 222+128=350, then 350+170=520, 520+218=738. Actually: 30 to 68 is +38, 68 to 138 is +70, 138 to 222 is +84. The differences increase: 38×2-6=70, 70×2-56=84. Continuing: 350 fits as 222+128=350, then 350+170=520, 520+218=738. The pattern of differences is 38, 70, 84, 128, 170, 218.

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