All 36 IQ & Logical Thinking quiz questions below come with a short explanation, visible right on the page — no sign-in needed. They're grouped by beginner and intermediate levels and 7 subtopics, so you can revise one part at a time. Choose Try IQ & Logical Thinking quiz above to take a scored run and review the questions you got wrong.
Answer: A
The answer is 13. This is the Fibonacci sequence: each number is the sum of the two before it (1+1=2, 1+2=3, 2+3=5, 3+5=8, 5+8=13).
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Answer: B
The answer is 5 thousand. Let the ball be x, so the bat is x + 100; then 2x + 100 = 110, giving x = 5. The answer 10 is an intuition trap: that would make the difference only 90, not 100.
Answer: B
The answer is 5 minutes. From the given we get each machine's rate: one machine makes one widget in 5 minutes. 100 machines running in parallel still take 5 minutes — machine count grows in the same proportion as widget count.
Answer: B
The answer is day 47. Since the area doubles every day, going back one day from full coverage leaves exactly half. The answer 24 is the linear-thinking trap applied to exponential growth.
Answer: A
The answer is 38. The differences are 3, 5, 7, 9 — increasing odd numbers, so the next difference is 11 and 27 + 11 = 38.
Answer: A
No conclusion is necessarily true. Both programmers and mathematicians fall in the group "logical thinkers", but these two subsets may overlap or be disjoint — the two premises don't determine it.
Answer: C
The answer is 90 degrees. The clock face's 360 degrees divided by 12 hour marks gives 30 degrees each; the minute hand is at 12, the hour hand at 3, three marks apart.
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Answer: B
The answer is 1/6. There are 36 outcomes when rolling two dice, and 6 pairs give a sum of 7: (1,6), (2,5), (3,4), (4,3), (5,2), (6,1). So 6/36 = 1/6.
Answer: C
The answer is Thursday. The cycle is 7 days, so only the remainder matters: 100 = 14×7 + 2, two days after Tuesday.
Answer: A
The answer is 312211. This is the "read it out loud" sequence: each number describes the one before it. Reading 111221 as "three ones, two twos, one one" gives 31 22 11.
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Answer: B
Answer: 2 weighings. Split 3-3-2: weigh the two groups of 3 against each other. If they tip, the heavy ball is in the heavier group of 3, so weigh any two of that group. If they balance, the heavy ball is in the group of 2, so weigh those two.
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Answer: C
Answer: 14 drops. Drop the first egg from floor 14, then 27 (14+13), 39 (27+12)... each step decreases by one floor. If it breaks, use the second egg to scan floor by floor within the interval just skipped, and the total never exceeds 14.
Answer: A
Turn switch 1 on for about ten minutes then off, turn switch 2 on, then enter the room. The bulb that is on belongs to switch 2, the bulb off but still warm belongs to switch 1, and the bulb off and cold belongs to switch 3.
Answer: D
Answer: 48 km/h. Average speed is total distance divided by total time, not the arithmetic mean. For distance d: time is d/60 + d/40 = d/24, so average speed is 2d divided by d/24, which equals 48.
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Answer: B
You should switch — the win probability rises from 1/3 to 2/3. The initial choice is correct with probability 1/3 and that doesn't change; the entire remaining 2/3 collapses onto the single unopened door.
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Answer: A
Answer: 17 minutes: 1 and 2 cross (2), 1 returns (1), 5 and 10 cross together (10), 2 returns (2), 1 and 2 cross (2). Total 2 + 1 + 10 + 2 + 2 = 17.
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Answer: B
Answer: 10 bulbs — bulbs 1, 4, 9, 16, 25, 36, 49, 64, 81, 100. Bulb n is toggled exactly as many times as it has divisors, and only perfect squares have an odd number of divisors, so only they stay on.
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Answer: A
Turn A and 7. A because the other side must be even. 7 because if the other side is a vowel the rule is broken. The 4 is useless: whatever is on the other side, there's no contradiction, since the rule doesn't say an even number must go with a vowel.
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Answer: C
Fill the 5-litre jug → pour into the 3-litre jug (5-litre jug now has 2) → empty the 3-litre jug → transfer the 2 litres into the 3-litre jug → fill the 5-litre jug → pour into the 3-litre jug (it only takes 1 more) → the 5-litre jug has exactly 4 litres left.
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Answer: A
About 50% (more precisely 50.7%). Intuition often gets this wrong because people count people, whereas what matters is the number of pairs: 23 people make 253 pairs, and each pair is a chance of a match.
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Answer: D
Answer 3 weighings. There are 24 possibilities (12 balls × 2 directions heavy/light). Each weighing gives 3 outcomes, so 3 weighings can distinguish at most 27 cases — just enough, and this is also why 13 balls cannot be solved in 3 weighings.
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Answer: A
Answer 10 mice. Number the bottles from 0 to 999 in binary; mouse i drinks every bottle whose i-th bit is 1. The combination of dead mice reads out the binary number of the poisoned bottle. 2^10 = 1024 ≥ 1000.
Answer: C
Light rope one at both ends and rope two at one end at the same time. Rope one burns out after exactly 30 minutes; at that moment light the other end of rope two, and its remaining part burns out in 15 minutes. Total 45 minutes.
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Answer: B
Answer 7 races. Five races for the 5 groups; race six runs the 5 group winners to find the fastest horse; race seven runs the 5 horses that could still make the top 3 — second and third of the winning group, first and second of the second group, first of the third group.
Answer: B
This statement cannot occur on that island. If the speaker is a knight, the statement must be true, meaning he is a knave — a contradiction. If he is a knave, the statement must be false, meaning he is not a knave — also a contradiction.
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Answer: A
Answer 45. Each person shakes hands with 9 others, giving 90, but every handshake is counted twice, so divide by two: 10×9/2 = 45.
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Answer: B
Equivalent to the contrapositive: "if the road is not wet, then it does not rain". The converse ("if the road is wet, then it rains") and the inverse ("if it does not rain, the road is not wet") are not equivalent.
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Answer: D
Take 1 stick, leaving 20 — a multiple of 4. After that, each turn take whatever makes the total with the opponent's take equal to 4 (they take 1, you take 3; they take 2, you take 2...). The sticks left always stay a multiple of 4, so the last stick is guaranteed to be yours.
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Answer: C
At least two people were born in the same month. Pigeonhole principle: placing 13 objects into 12 slots guarantees some slot holds two or more.
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Answer: A
Answer 720. This is the factorial sequence: 1, 2, 6, 24, 120 are 1!, 2!, 3!, 4!, 5! respectively, so the next number is 6! = 720. The multipliers increase: ×2, ×3, ×4, ×5, ×6.
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Answer: C
One fruit, drawn from the box labelled mixed. Since that label is wrong, this box holds a single type, and the fruit drawn tells you which. The other two boxes follow by elimination, since each has only one remaining possibility that doesn't match its own label.
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Answer: C
8 days. The snail gains a net 1m per day, so after 7 days it is at 7m. On day 8 it climbs 3m, reaches the top and gets out, so there is no further slip.
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Answer: D
7 pieces. The first cut makes 2, the second crosses the first and adds 2 more for 4, and the third crosses both previous cuts at two distinct points, adding 3 more, for 7 total.
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Answer: A
2 hours 24 minutes. Add rates, not times: tap A fills one quarter of the tank per hour, tap B one sixth, together five twelfths. The time is the reciprocal, twelve fifths of an hour.
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Answer: A
11/36. The fastest way is the complement: the probability of no six at all is five sixths times five sixths equals twenty-five thirty-sixths, so the answer is one minus that.
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Answer: A
No dollar is missing — the addition goes the wrong way. The three people paid a net 27, of which 25 went to the hotel and 2 to the clerk. Adding 27 and 2 double-counts the clerk's share; the correct check is 27 minus 2 equals 25.
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