Question
A was travelling from point X to point Y. He increased
his speed by 14 km/h after every hour. He reached his destination in 18 hours. If his initial speed was 20 km/h, then what was his average speed in the whole journey?Solution
Total distance travelled by A = (18/2) × {2 × 20 + (18 – 1) × 14} = 14 × (40 + 238) = 2502 km Required average speed = 2502/18 = 139 km/h
The sum of the first 10 terms of an arithmetic sequence is 60 and the 10th term is 5. What is the first term of the sequence?
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3600, 600, 120, 30, 10, ?
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In an arithmetic progression, the 4th term is 23 and the 9th term is 48. What is the sum of the first 20 terms?
If p:q = 5:7 and p + q = 408, then find the value of (q - p).
