Math Riddles Page 9 of 26
Math riddles and Problems to solve, there's a wide variety of types and difficulty, use your expert math skills to solve them.
81. My father is three times as old as my sister, who is twice as old as my brother, who is twice as old as our nephew. The total of all ages is divisible by five and less than 100. How old is my father?
82. Kevin treated his girlfriend to a bus ride, but because of his limited resources they had to walk back. Now, if the bus goes at an average speed of 9 miles per hour and they can walk back at the rate of three miles per hour, how far did they ride so that they made it back in eight hours?
83. Using the numbers 1 through 9, how many three-digit palindromic numbers can you make? A palindrome reads the same forward and backward. Examples: 181, 545, 858.
84. Which set of numbers would most logically come next in the following sequence?
10 1 9 2 8 3 7 4 6 5 5 6 4 7 3 8 2
(a) 9 1 (b) 9 3 (c) 8 5 (d) 6 7
85. Can you think of a geometric series of whole numbers with three or more numbers which add up to a square? Start with 1. Example: 1 + 3 + 9 + 27 + 81 = 121 = 11 squared.
86. Two ferries start at the same time from opposite sides of a river, traveling across the water on routes at right angles to the shores. Each boat travels at a constant speed, though their two speeds are different. They pass at a point 720 yards from the nearer shore. Both boats remain at their slips for 10 minutes before starting back. On the return trips, they meet 400 yards form the other shore. How wide is the river?
87. What is the significance of this sequence?
235, 711, 131, 719, 232, 931, 374, 143
88. A man left a legacy of $10,000 to three relatives and their wives. Together, the wives received $3960. June received $100 more than Camille, and Martha received $100 more than June. Jack Smith was given just as much as his wife, Horace Saunders got half as much again as his wife, and Terry Connors received twice as much as his wife. What was the first name of each man's wife?
89. What is the number that is one more than one-fifth of one-third of one-half of one-tenth of 2,700?
90. What is the number which is 5 more than one-fifth of one-tenth of one-fourth of 1000?
