1. The researcher observed that the cells in her experiment were irregular in shape and appeared very changing shape continuously.
A. glabrous
B. torpid
C. granular
D. homogeneous
E. labile Correct
Explanation
Labile means prone to change or instability, which directly describes cells that are 'changing shape continuously.' Glabrous means smooth-haired, torpid means sluggish, granular means grainy, and homogeneous means uniform-none of which describe constant change.
2. What is the product of the two solutions ofthe equation 3x^2+8x-3=0?
A. -3 Correct
B. -1
C. -(1/3)
D. 1/3
E. 1
Explanation
For a quadratic equation ax² + bx + c = 0, the product of the roots is c/a. Here, a = 3, c = -3, so the product is (-3)/3 = -1. However, the options include -1, but the correct calculation is -3/3 = -1, which is option B. The equation is 3x² + 8x - 3 = 0. The product of roots is c/a = -3/3 = -1. So the correct answer is -1, which is option B. Therefore, the product is c/a = -3/3 = -1.
3. Toys were packed into x boxes so that each box contained the same number of toys, with no toys left unpacked. If 3 fewer boxes had been used instead, then 12 toys would have been packed in each box, with 5 toys left unpacked. What is the value of x?
A. 11
B. 14
C. 28 Correct
D. 31
E. 34
Explanation
Let the number of toys be T and the number of boxes be x. Then T/x = toys per box. With 3 fewer boxes, we have (x-3) boxes, 12 toys per box, and 5 left unpacked: T = 12(x-3) + 5. Also, T = (T/x) * x. So 12(x-3) + 5 = T. Since T is divisible by x, substitute: 12x - 36 + 5 = T, so T = 12x - 31. Now T must be divisible by x, so 12x - 31 is divisible by x, meaning 31 is divisible by x. The positive divisors of 31 are 1 and 31. x cannot be 1 because 3 fewer boxes would be negative. So x = 31. Check: T = 12*31 - 31 = 341. Then toys per box originally = 341/31 = 11. With 28 boxes, 12*28 = 336, and 341 - 336 = 5 left unpacked. Correct.
4. Of the positive integers that are less than 25, how many are equal to the sum of a positive multiple of 4 and a positive multiple of 5?
A. 2
B. 5
C. 10
D. 11 Correct
E. 22
Explanation
We need numbers n < 25 such that n = 4a + 5b with a,b >=1. The multiples of 4: 4,8,12,16,20,24; multiples of 5: 5,10,15,20. Possible sums: 4+5=9, 4+10=14, 4+15=19, 4+20=24, 8+5=13, 8+10=18, 8+15=23, 12+5=17, 12+10=22, 16+5=21, 20+5=25 (but 25 not <25). So the numbers are: 9,13,14,17,18,19,21,22,23,24. That's 10 numbers. But 24 is included (4+20), and 20 is a multiple of 5. So answer is 10, option C. However, the user's answer was marked as 11, which is incorrect. The correct count is 10.
5. In the figure, line and the x-axis are tangent to the circle at points P and S respectively, and line segment QS passes through the center R of the circle. What is the slope of I?
A. 1/2
B. √3/3
C. √3/2
D. 1 Correct
E. √3
Explanation
In the figure the x–axis and line ℓ are tangent to the circle at S and P, and QS is a line through S and the circle’s center R. Because QS contains the center and meets the x–axis at S, QS is the vertical radius through the tangency point S. The radius to a tangent point is perpendicular to the tangent, so RP (the radius to P) is perpendicular to ℓ. The marked 45° at P indicates that the angle between RP and the vertical radius RS is 45°, so the angle between RS and the tangent ℓ is 90° − 45° = 45°. Since RS is vertical, the angle ℓ makes with the horizontal is 90° − 45° = 45° + 15°? — equivalently, careful triangle analysis of the right triangle formed by R, P, and the foot on the x-axis shows the acute angle between ℓ and the x-axis is 60°. Therefore the slope of ℓ equals tan(60°) = √3, so the slope is √3.